I also have the Canon 430EX and recommend it. It's fully compatible with your camera and it's a great unit. It's not really cheap though. The 580EX would be a step up but it's even more expensive.
There are other flash units that are compatible with Canon's flash metering. Sigma, Metz and some others have models that are 'E-TTL' compatible or 'Dedicated' for Canon. I haven't used any of these, so I can't say for sure, just how compatible they are.
Another option, would be to get something like the Sunpak 383. It's a fair bit cheaper than the 'dedicated' flash units...but it doesn't communicate with the camera for flash metering. You have a few settings on the flash, which would have to be matched up on the camera, in order to get proper exposure. So you could save some money...but you would need to learn how to use it, for it to be quick and easy to use.
It's much easier to use a model with E-TTL metering.