hey i saw your page and thinking that you might help me=)
i just bought a canon s5is
i want to get accessories for it
like the filter and lenses
anu bang masusugest nyo?? for a begginer like me...
i need a reply guys.. 
Wow, I would have gotten myself one of those din had financial matters allowed me too. Neat toy. For now Im only particular about the S3IS, but if you can confirm, here are the stuffs I found that fit your query..
Adapter, P2100 - most basic, for you to be able to mount a UV filter, wide angle converter and a teleconverter you need this, it also comes with a bayonet hood.
UV Filter around P500+- you can live without this since it causes some stacking on your photos, if you attach the lens hood with a UV filter in between the adapter, but to protect your one and only lens, I'd say screw the hood and buy one of these. :D
Wide angle and Teleconverter, turns your 36mm to 24mm (or something like that) (7k+-)and your 436mm (or something) x 1.5x or 650mm or something. LOL!
You cant really change the lens, only add converters to it. :)
Big memory cards, a good enough cam bag (crumpler), some batteries a fast charger and probably a nice tamrac strap would also be one on my list.
I havent tried the proprietory flash but since may TTL na yan, try scouting for one as well.
