Do you belong to any chat forums? Tell your virtual friends about your book. Put a link or title of the book in your signature. It doesn't have to be heavy selling, just mention it.
Facebook, Myspace and Yuwie are all examples of social networking sites where people blatantly promote themselves. Some do it with more finesse than others, but everyone wants to be noticed and so they will make an effort to look at your page too, just to be sociable. Yuwie users have the added incentive of being paid for page views, so they are a very friendly bunch. In addition, Yuwie is flooded with ideas for promotion of anything under the sun!
The main thing you need to do is to set up your page on any of these sites. This will include a photo of you (or whatever picture you like, it could be your book cover), your interests and your contact details (which can include your book's web page or your blog). It is up to you how much information you provide or make public, but don't make it too hard for people to see your page, or you'll defeat the purpose. Then, it is time to meet people. Contact on these sites is usually pretty "light" and uncomplicated, not too stressful at all.
Social networking sites have groups or clubs, which you can easily start up, or join. The groups cover many topics and you will easily find one or more which might have an audience for your book. There are also author promotion groups, which sometimes have good information.
Lulu and Amazon have widgets which you can install on your social networking site to feature your books. The Lulu Facebook widget is quite nice and extremely easy to add. (A widget is a piece of code which they provide, and which is usually quite easy to install.)