I use a Panasonic TZ1. A bit bigger than the optio S (but not by much):
- 10x optical zoom (the smallest camera available with a 10x zoom I believe);
- optical image stablisier that works (I'm yet to ave a blurry shot, even at maximum zoom);
- 5 MP
It really has been a fantastic camera for me so far. The quality of the Leica lens is very good and I ca honestly say I've not yet had a bad shot.