The second and final round of BlizzCon tickets go on sale this Saturday, May 30, and I'm pretty sure they'll go fast - the first round sold out in half an hour. However, if you miss out on a ticket (or if you think they're just too expensive), you may have a chance to go anyway.
Wowhead, along with APC (makers of UPSes and such), is running a contest over the next few weeks, with a drawing every day until June 18th. June 17th is the last day to enter; all you need to do is fill in your contact details on the contest page, and you're automatically entered for every drawing. Sadly, this contest is only open to US residents age 18 and older ("we know it sucks," Wowhead says).
Oh right, the prizes.
There is one grand prize, consisting of two tickets to BlizzCon, along with air fare and accommodations, an APC UPS, and a dinner with the Wowhead folks. Three lucky first-prize winners will get their choice of a Wii, a PS3, or an Xbox 360, as well as an APC surge protector. And every day that those prizes aren't given out, someone will win a Wowhead t-shirt and an APC surge protector. One of these last winners will be randomly chosen to win a Blizzcon ticket as well, at the end of the contest.