How do I retrieve my stats for a given word or character, without looking through the viewer to find it?

A search feature would be nice. For example. Where you could type 你, and your stats for 你，你们，你好 (etc.) would come up.

I agree. The list viewer is very difficult to manage without any search mechanism, especially when you have hundreds of entry in it.
By the way, such a feature is not a priority for me.

We can put that on the list of things to do. For now, I guess you could use a kind of a hack.

The url structure for the individual word viewer is:

http://www.skritter.com/useritem/zh//0

So just replace with whatever word or character you want to look at. This will only work for simplified characters. So here's an example

http://www.skritter.com/useritem/zh/那个/0

The 0 means it'll go for the simplified (greater than 0 means traditional), but from there you'll get a list of traditional words that are associated with it so you can just click through to them.

A search feature shouldn't be too hard to implement, so hopefully you won't have to use this hack for too long!