headind to ko samui in 1 week. are there good snokeling trips there? can anyone recommend a day sailing trip or speedboat trip?

Samui it self does not have any good diving or snorkeling but there are dive sites around Samui but you'll have to charter a boat or join a dive trip to reach these area. Try searching the web for more information or try this website: http://www.sawadee.com/diving/

If you like golf Samui has a very good golf course half way up the mountain.

Oops I posted the wrong website. Here's the correct one: http://samui.sawadee.com/oceansports/index.html

Lots of day trips to Koh Tao which is good for all types of diving. That link Hanuman has given is good and you can find other attractions, thy these too:-

http://www.samuitourism.com/attractions/index.htm

http://www.samuitourism.com/tour/mr_ung/index.htm

http://www.seacanoe.net/samui.htm

ttt for whoever was asking about Samui trips