Almost all the good ones do, or so I hear. To the best of my knowledge there are no 'good' and 'free' options. Well, maybe CloudOn and OnLive, but those only work if and while you have a good internet connection. If you can live with that, give them a try.
Otherwise, the better apps are:
iWorks (Pages, Numbers, Keynote) (my choice)
Documents to Go
QuickOffice
Office HD
Polaris Office.