I'm interested in putting a bike rack of some sort on my 2006 S40. Considering a Thule roofrack type set up (since I could use that for skis as well) or something on the back. Does anyone have any input/suggestions? Thanks!!!

I use Thule on my S40. The initial investment is a little pricey, because you gotta buy load bars, feet, a fit kit, and then the attachments. But you have so many attachment options that it works out in the end.

I have setups for:
Ski
Snowboard
Surfboard
Bike

Very versatile. You can buy the same stuff from Volvo in their parts dept that will say Volvo instead of Thule (both Swedish) but just find an outdoor outfitter and look for a 10-20% off sale sometime. Also, people are always selling stuff on Craigslist so maybe you can buy the load bars or bike rack on there, and just have to buy the fit kit new.

Yakima is okay, too, but I prefer Thule.