Worm bins are actually fantastically easy. Not only are they easily in the space and discretion requirements of a college student couple living in an apartment complex, they are easy to maintain, and their habitat is low cost. We ended up using one of those big Rubbermaid bins and drilling air holes in it. Rather than describing how to make a worm bin I'll give you some links that include a few options.
http://whatcom.wsu.edu/ag/compost/Redwormsedit.htm This link is to a university site on specific information about worm care, and the necessities for their environment and care, as well as a few rules of thumb. A very thorough site especially for the more scientifically minded.
http://whatcom.wsu.edu/ag/compost/easywormbin.htm Associated with the first site a pictorial set of directions on how to construct one variety of worm bin. We actually went with a more simple set up than this one using only one bin. The two bin system is in theory easier to harvest your dirt from, and may in fact be a very good idea.
http://www.wikihow.com/Make-Your-Own-Worm-Compost-System This link has a few options for how you can make your bin without the handy pictorial of the above site. It includes the basic system we have of a single tub with holes drilled a bit up from the top.
http://www.oregonmetro.gov/index.cfm/go/by.web/id=554 This site has much of the same information as above two sites, but their PDF includes directions on how to make a wooden worm bin, and simple directions on making a plastic one like we have.
So far we've had great experiences with our worm bin other than a few minor hiccups. In the apartment we ended up keeping it in the bathroom as just about the only place we could assume would stay cool enough in the summer, and warm enough in the winter. The first hiccup we had was that it was moist enough that if we put much fruit or moist vegetables in, it would smell a bit funny. Not terrible, but noticeable. We fixed it by putting a bit more in the way of dry things in there with the bin to keep from having too much moisture leading to that funny smell.
Our second hiccup was a bit more serious, and annoying. Fruit flies. One day we put in some banana peals from the lady of the house having produced some delicious banana bread. About 4 days later, we had fruit flies by the hundreds in the upstairs bathroom. It wasn't quite to plague proportions, but it certainly seemed like it at the time! After some trial and error we both figured out how to efficiently trap fruit flies and kill them, and how to avoid the problem in the future.
How we have avoided the problem since for the most part is a fairly simple two piece solution. First, we freeze the fruit leftovers before we put them in the bin. Second, we only put in a little bit at a time. The obvious problem with this is making sure we don't have a sudden run of fruit to go in the bin at once, and having a freezer available. That said, that particular solution has ended up working perfectly.
The benefits of the worm bin are fairly clear. We don't throw away vegetable trash unless it is mixed with meat oils and fats. Those vegetables that would have ended up in a land fill normally where they'd rot producing harmful gasses are instead broken down into amazingly good soil that will eventually go to our garden. The first bucket we harvested from the worm bin was so fertile ended up growing things in it while it was sitting and drying out before being used. I personally don't know the scientific specifics of it, but I do know that worm compost is just about the best compost you can get for your garden. We figure we'll probably use the worm bin for the rest of our lives and just keep our waste down, and our garden happier.