I have the Plantronics in-ears mentioned by slogo, they’re pretty decent sound wise but the battery life is atrocious – i get less than 3hrs use before they run out of juice. I bought them for bike use but the fit is not fantastic and being in-ear phones they need to have a good seal to get any bass out of them – personally i’d avoid them.
I also have these Sennheiser mm100 that i use at work and on the bike – i’m quite happy with these but they ain’t a patch on decent wired headphones and there is no isolation from outside noise.
How much do you wish to spend? – I’ve listened to these sennheiser mmx400 before and they sound very natural and open, decent bass response and decent battery life.