Surprised noone has mentioned the Kershaw Chill or Skyline (the latter is about $30-35). Both are very nice thin flipper knives around 3" blade although NOT the strongest knives obviously. In the semi-traditional arena there are other choices such as the Douk Douk and Mercator. Both are quite slim and light. Nice carbon (non-stainless) steel too. Have a Mercator and though it took a little work to make it work to my satisfaction is a nice knife to use and use and use. The Douk Douk has less of a traditional droppoint blade but still very usable.
If small is what you want... why not try the SRM 681? One of the handiest little knives I've owned, used it all the time at work and noone ever noticed the very tiny pocket clip. However, the retention is NOT as good as a wider, strong clip would have but more than adequate. Avoid the 614 (?) and the other one-side (no non-locking side) liner/framelocks from SRM, total junk.
