I've got a Uniross AA charger that charges 4 AA's in 2 hrs. The batteries come out of it really hot though. Had it for a few years but i cant remember them getting so warm as they do now, but i could be mistaken.

Are they (the batteries) meant to get really hot, or are the batteries / charger knackered. They seem to hold their charge ok and are 2300mAh.

Fast charging does generate heat. Over heating causes damage and might be a sign of overcharging. Some posh chargers monitor temperature and use a rapid increase as sign the cells are full. Hard to say if yours is 'normal' or too much. If you are getting 2.3Ah out then I shouldn't worry too much.

My AA battery charger has a built-in fan to keep the batteries cool as they charge.

I used to have a cheap Uniross charger that had no monitoring and used to completely cook batteries if u weren't careful. Do you know if your charger actually has any 'intelligence'?