Whats good whats not? Im looking at replacing my laptop for one.
Linux preferred tbh so I can use my favourite linux based C compilers

Price - about 200-250 tops 300 if im really pinching

I'd imagine they're all pretty similar, I'm not really up to date, so I suggest you read some reviews.

Your price range is pretty easy, though. The only thing that may be a concern for you is the screen size limiting amount of viewable info? I know it's one "problem" I get with my laptop.

Im thinking of the £250 Eeepc 9" (im only using it for coding really)
6.5 - 8 hour battery life which is good

That's a pretty sweet battery life. I know I get 3-4hours on my lappy, which is above average (and sometimes, just not quite enough), so that is amazing.

What res is the screen?

1024x640

Not too bad, can get a air bit on there. Depends how much you like to have on screen at once, I guess. I say go for it (just read some reviews first), their portability is certainly a massive plus

I personally favour the Dell Inspiron Mini 9.