From Inspiration Green:
Tidy gardens, chemically fertilized lawns, and 
a lack of dead wood in suburban/urban areas mean less and less habitat for wild bees, spiders, and
 ladybugs. You can combat this issue by creating an "insect hotel" to attract beneficial insects (read: pollinators and pest controllers)  to your yard and garden. Read on for some beautiful ideas!
Honey bees
 represent only a small fraction of the approximately 20,000 known 
species of bees. No honey bees existed in the Americas before their 
introduction by Europeans. An insect hotel will attract these and many other kinds of bees, as well as hundreds of other beneficial insects.
 
Insect hotels are also known as:
Bug
 condos, bug hotels, insect habitats, wildlife stacks, insect boxes, 
insect houses, insect walls, wild bee walls, insect accommodation, wild 
bee houses, solitary bee walls or wild bienenhaus.
Who lives in Insect Hotels:
Wasps (cuckoo wasps, parasitic wasps, and many other kinds), dragonflies, beetles, lacewings, ladybirds. moths, spiders, frogs, newts, hedgehogs, and bees (leafcutter bees, masked bees, mason bees, digger bees, bumblebees, and hundreds more).
Another thing about bees:
Bumblebees
 nest in hollow trees and in rodent burrows. They are among the first 
bees to emerge in the spring and the last to disappear in fall. They are
 superb pollinators of tomatoes, blueberries, cranberries, clover, and 
more. Bumblebees can “buzz pollinate” by hanging on a flower and 
vibrating with their flight muscles to release pollen. Mason and 
Leafcutter Bees select existing hollow stems and bored holes in which to
 build their multiple nest chambers. They carry pollen underneath their 
bodies rather than on their legs like most bees. Mason bees are 
first-class pollinators of many fruit crops, toiling long hours and in 
inclement weather. Squash and Gourd Bees help pollinate up to eighty 
percent of squash, pumpkins, and melons. They are ground nesters, so it 
is important to leave some open dirt for the these very important bees 
as well.
The Photos
Here are some photos of particularly amazing insect hotel designs. The basic execution of the idea can be facilitated using scraps and things you have lying around your garden shed, garage, or yard. Check these out:
   
A wildlife stack can harbor numerous beneficial insects and amphibians. 
www.metrofieldguide.com
Wildlife
 stack. Some creatures like it damp, others (like bees) dry. Ladybugs 
hibernate during winter in piles of dry twigs and leaves, which you can 
provide in your insect hotel. Might be better to think of it as habitat 
or a condo, as you really want long term residents. 
Photo by Sarah Barker at the Shrewsbury flower show.
Bug
 hotel in Oakham, UK. Although often called a hotel, some bees will live
 in a nest for up to nine months as they develop from egg, through the 
larval stage, into adulthood. Photo by Anne Crasey. 
www.flickr.com 
Solitary
 bees like sun. The ideal location for an insect hotel is in full sun 
and protected from the weather. This will ensure that the heat required 
for the brood is present, and wind or rain will not destroy their nest. 
Provide that, and the flowers, and they will come. 
www.sav-überlingen.de
Insect hotel in Hamburg, Germany. Wild bee houses have been popular in Europe for many years. 
insektenhotel24.de
Insect hotel at the Heimanshof, North Holland.
Many
 solitary bees are very small and you may not have realised they are 
bees. More species of bees live alone, than in hives. Wild bees are 
considered to be as important to the food chain as bumblebees and 
honeybees. Honey bees are not native to the Americas (see below). Photo 
by Bob Daamen 
www.flickr.com.
Insect
 home or bug bank, on the grounds of Oxburgh Hall in North Norfolk. 
Because solitary bees have no hive to defend, they are not aggressive, 
they rarely, if ever, sting. Photo by Mabvith 
flickr.com.
Insect hotel in Helmsley, UK. 
Hotels should be relatively close to flowering herbs, wild flowers and native shrubs and trees to cover the food needs of the insects. Photo by Munki Munki, 
www.flickr.com.
Solitary bees
 are different from social bees (such as honey bees) in that every 
female is fertile and makes individual nest cells for her offspring. 
Some native bees are ground nesters but more than 30% are wood nesters. 
The female wood nester will look for pre-existing cavities such as 
hollow stems or holes in wood that are just the right size to use as a 
nest. 
The female typically creates a series of compartments 
(cells) and within each cell she will lay an egg on top of its future 
food source. The female bee will make numerous foraging trips to flowers
 collecting pollen and nectar that she will pack into each cell. It is 
on these trips that the female wild bee acts as a pollinator for plants 
and food crops. It can take anywhere from 20 to 30 trips to fill each 
cell with food. When she is satisfied with the amount of food, she lays 
an egg, compartmentalizes the cell, and moves on to creating the next 
cell. When she feels the chamber is complete, she seals off the end, and
 moves on to filling a new chamber. The last cells (those closer to the 
opening) contain eggs that will become males, as males hatch before 
females. Although each species is different, mason bee females live for 
about a month, and can build a cell nest for about two eggs every day. 
The larva hatches from the egg after a week or more and begins to eat 
the provided pollen and nectar. After the food has been eaten, the larva
 spins a cocoon and pupates within the cell. By the end of summer or 
early fall, the bee transforms but remains in the cocoon as an adult 
throughout the winter. In spring, the males begin to emerge by chewing 
their way out. The females, which are almost always in the deeper cells 
of the tunnel, emerge a week or two later. 
While solitary 
females each make individual nests, some species prefer to make nests 
near others of the same species, giving the appearance to the casual 
observer that they are social. Nest photo by Mike N. of Vancouver, BC.
Insect
 hotel in Hoofddorf, Holland. Drilled 4 x 4s, logs, twigs and 
sticks. There are many different species of solitary bee, all are 
excellent pollinators. Photo by Bob Daamen, 
www.flickr.com
Insect hotel in St. Poelten Landesmuseum, Austria. That shutter will keep the birds out. Photo by Klasse im Garten, 
flickr.com.
Bug stack. Keep an eye on activity as some ants will eat bee larvae.
Insect Hotel.
Bug Mansion.
Ladybugs
 are always looking for places to hide and escape from the weather. By 
the Harrogate District Biodiversity Action Group. 
Wildlife stack by Dawn Isaacs. How-to: 
www.guardian.co.uk
Insect Condo in Scotland.
Photo by Sheila, flickr.com

Wild Bee Hotel in Austria.

Bee Condo.
Photo by Sissi de Kroon, flickr.com

Insect Hotel in a private garden in Austria.

Insect Hotel, Ebersberger Forest, Bavaria
Photo by Terry Cooke, flickr.com.

Insect Hotel (Zen-like)

Place cut bamboo in metal pipes.
Photo by Bob Daamen. www.flickr.com

Wire screening keeps the small stuff in place and protects against birds. 
Photo by Joeke Pieters, flickr.com

Wild bee house in the Black Forest, Germany. Photo by Michael Bohnert. www.flickr.com

A fun learning project for kids.

Insect hotel in the Netherlands, close-up.
flickr.com

An 'Insect hotel' at the Durrell Wildlife Conservation Trust in Jersey ©RLLord, 

Insect
 Habitat assembled from foraged organic materials and reclaimed scrap, a
 habitat-in-waiting for bees and other native creatures. By Kevin Smith 
and Lisa Lee Benjamin. floragrubb.com

Insect Habitat at The Garden Tulln, Austria.
www.flickr.com
Insect Hotel in Germany.
www.wildbienen.de

Bug hotel by Lisa and Andrew Roberts (Living Willow Wales) at Ysgol Pontrhydfendigaid. andrewroberts.net

Bug hotel created by kids at the RHS Flower Show, Tatton Park. flickr.com
 
How To:
(A Must Read: Our Polinators Need a Home!)
For
 a simple hotel, drill holes 1/4" to 3/8" in the ends of logs, or cut 
some bamboo sticks of equal length, and stuff in a wooden box. Layer old
 pallets. Logs,
 drift wood, cut bamboo, straw, dry reeds, roofing tiles, cob. Do not 
use softwood for bees, as the drilled holes might fill with resin and 
suffocate the bees! Make sure all wood is free of chemical preservatives.
Further Reading: 

Lots more inspiration here: flickr.com/groups/insecthotels