I'm looking to get a flash for my Canon Rebel. That way I have something better than the pop up flash. But i'm at a complete loss as to what to get. Any suggestions?
If you want to use TTL functions, go with the Canon 420 or 550 for sure. The 550 is worth the extra money. I have the 420 and am already thinking of upgrading.
If you are looking for a less expensive option. There is a range of less powerful flashes that will work. There are smaller Canon Speed-light flashes or you could look at something like a Vivitar or other 3rd party. Any dedicated (made for Canon) hot shoe flash will be better than the pop-up on your camera.
Of course, the top end units (420, 550) are really the best if you can afford them.
Before getting my DLSR, I went real cheap and got a sunpack 355AF. Good results but the biggest hassle was the manual zoom. At around $50 its a pretty cheap way to go
Several companies make dedicated flash units that will work with Canon Rebel series cameras. The less expensive units will not have exposure compensation. If you want to use them for fill, you have to change your aperture, which will change your photo composition. Or experiment with covering the flash head with tissue, etc.
In short, if you can wait until you can afford a Canon 420 or 550, you'll be glad you did.