Join Date: Mar 2008
Location: San Francisco CA
Bikes: 2008 Specialized Sirrus, 1973 Raleigh Gran Prix
The best advice I've seen whenever this question comes up is to go to as many reputable local bicycle shops (LBSs) as you can, tell the sales staff what you're planning to use the bike for, let them make recommendations, and test ride lots of bikes. Remember that most LBSs only carry a few brands, so don't buy from the first place you visit and be sure to visit as many as possible so you can ride as many different brands and models as possible. I also found it useful when different bike shops carried the same brand(s) of bike to ask them both what they think about particular models from that manufacturer to see if they say different things. Before you buy, you should do a search on this site for the manufacturer and model of bike(s) you're considering buying. You can also look through this forum for other "what bike should I get?" threads. There are lots of them. While your considerations may be different than those of other people, you can learn a lot about what bikes people on this forum like by seeing how this question was answered in other threads.
The most important thing is that the bike fits. Since different manufacturers make bikes that have different geometries, ride lots of different bikes and remember that a bike that is a great fit for a bike salesperson (or for someone at this forum) might not be the best fit for you.
Having said all that, I bought a '08 Specialized Sirrus (base model, $529; 2009 prices are different, I think, and the specs may be different as well) because it had the geometry of a road bike, it had flat bars (it's called a "performance," as opposed to a "comfort," hybrid) and it has relatively thin (28c) tires. Other hybrids might be more like mountain bikes (fatter tires, maybe even front fork shocks). Since you may do more off-road riding than I do (pretty much none), you might also consider a cyclocross bike, which is built for both speed and off-road riding.
Again, the most important thing is getting the best fit for you. That means visiting as many LBSs as you can and test riding as many bikes as you can and always remembering that what's right for someone else may not be right for you. Good luck!