It's not much, but there is a short article at Wikipedia talking about how the term beta reader
I have a very small baby (so I'm not as reliable as I once was) but you can always give me a shout and I'll try to beta for you on something resembling a timely basis. That doesn't mean a month before you hear anything back, but it might not always be the same day that you receive comments, especially if the baby is teething. (Ugh, poor little thing.) With that in mind...
However, before you choose to work with a beta, I think you should get a feel for the sort of writing they do themselves, or exchange the first fics on a provisional basis before both parties commit to a longer-term beta relationship. A bad combo can be horrible.
If you are still looking for a regular beta, feel free to check out the
fics (just felt like that needed some self-depricating humor since it sounds like I'm pimping my fics) I've been posting for my doctorwho_100 challenge table
and see if you think we might have a similar feel for things. If running a quick eye over a longer fic might give you a better idea, then you should peek at a Harry Potter fic of mine
(Roses in December is the one I think is the best representation of what I'm all about) and see if you think I might have a perspective to add to the writing you will be doing. Seriously, if you read that stuff and hate it, then there's nothing I would be able to add to your work.
Of course, you don't want two carbon copy writers, but you don't want two diametrically opposed writers, either...but that's neither here nor there. You know what I'm getting at, I think.
Just reply to this comment or to a random post in my LJ if you would like to throw some fic back and forth. I'm game.