UPDATED: June 2012
Dragon*Con is considered the largest multi-genre media/pop culture convention in the world because it caters to so many different crowds. It's not just for anime, costuming, or sci-fi; it's all those things wrapped up into one big party that runs continuously for 5 days. Most conventions, especially the smaller ones, have a few key events like a costume contest, movie screening, or banquet. Dragon*Con has over 30 official programming events running simultaneously at any given time! And this doesn't even include the ongoing events like dealer rooms, autograph signings, or merely people watching in public areas.
The best analogy I can think of to describe fan tracks is college majors. Each track is like a major, with its own subset of events that are based around a central theme. Let's pretend you're attending Dragon*Con University, the best institution for anyone who geeks out over something they love. And let's say you're mostly there because you're a Star Wars fan. You check out the Star Wars fan track website and see that there's a ton of events running from 10:00am Friday until 5:00pm Monday, JOY!! No doubt you'll start your weekend off with a Q&A panel with Princess Leia herself, Carrie Fisher. But then you're not too thrilled about what's next, a fan discussion about how Star Wars Legos toys have affected the fandom. So you look at the Pocket Program and see that the Costuming Track is having a panel on basic costume making. You've always wanted to wear a costume but never knew where to start, and here is the perfect opportunity to learn the first steps! Over the next few days, you still get a heavy dose of Star Wars: Lightsaber demonstrations from professional performers, trivia contests, discussions about the extended universe from books and games. But somewhere in there, you've also checked out anime screenings, science lectures, book readings, and *GASP* a panel with William Shatner because you don't actually hate Star Trek. You still get to "graduate" with your Star Wars major, but you've also learned a lot about the other fandoms. Likewise, there's about 40,000 other graduates, each with their own unique area of study. Some focused on Young Adult Literature, others on Tolkien's Middle Earth, and some who took an equal amount of everything! The only drawback to Dragon*Con's diverse "curriculum" is that you'll sometimes have to choose between two things you love. I've had to forgo seeing a Farscape panel so I could catch geek goddess Felicia Day.
If you want to learn more about what tracks are available, check out this page:
Some of them update more frequently than others. Plus, a few tracks have already posted their tentative schedules for this year. It sure beats waiting until the week before D*C to make a rough schedule for yourself. Just keep in mind that times, rooms, and even participants are subject to change up to the day of that event.