A lot of my information about Universal Studios comes from following the Orlando Informer blog. Not only do they post some great news and updates about Disney and Universal, but probably the best thing they have is the Crowd Calendar.
The Crowd Calendar is just that, it is a crowd calendar featuring both the times of Universal Studios and Islands of Adventure, along with how busy the parks will be. They base this on past attendance, as well as weekends and special events. I have used this time and time again to plan when it is best to go down to Universal, and when it is not.
So if you are planning a trip to Universal Studios, make sure to check out the Crowd Calendar from Orlando Informer. And while you are on their website, poke around as you will probably learn a ton of tips and tricks for getting around in Orlando.