Although I think they are rather kitsch, if you are into buying one of the world famous Cuckoo clocks, you are in the right place. Geneva has thousands -- should I say millions? -- of Cuckoo clocks for sale. Prices vary a lot. From cheap 10 dollar clocks to antique clocks that can cost thousands of dollars. The best place to find these "jewels" is the area between the train station and "Pont Mont-Blanc".
Other souvenirs, that probably will be more appreciated by your friends and relatives, are items with the Swiss flag --like T-shirts and caps.
For bon vivant friends, buy a good local wine. Geneva region is surrounded by vineyards that produce excellent wines.