Canon Speedlite Help Please

[Cougar]

Ok as title says, I'd like some opinions on a Speedlite. I kind of need one (need being a relative term...) but would love some advice on which would be best for my situation.

I currently have a 500D, sigma 17-70, canon kit 55-250 and the 50mmm 1.8. Apart from learning how to use a speedlite as a skill I'd like to have, low light performance on the 500 is not great and I'd like to be able to expand that range with good flash (not that hideous pop-up thing and I can't push the ISO too high, the noise is too bad). I'd really like to upgrade to a 7d at some point but its not on the cards for a while yet, so figured a proper flash would help me.

So any advice would be greatly appreciated :) Thanks!