Looks like you've already got a couple of assisted-openers, back lock, frame lock, Arc lock, flipper opening, thumb stud, and thumb hole.
A couple other locks to try out are the liner lock, Axis lock, and compression lock. Check out the Kershaw Skline, which is a manual flipper w/ G10 handles and liner lock. The Benchmade Griptilian (or Mini-Griptilian) is a good knife featuring the Axis lock. The Spyderco Paramilitary 2 uses the compression lock and also has G10 handles. The Spyderco Manix 2 uses a ball bearing lock, which is similar to Benchmade's Axis lock. The Opinels use a ring lock, which is pretty different.
If you're interested in different steels, the Griptilian and Para2 use 154CM and S30V respectively. The Opinels have an option of coming in carbon steel, if you want to try out a non-stainless steel. You can also look at the Spyderco Delica, which comes in VG-10 or ZDP-189. The Kershaw composite blade Junkyard Dog or Rake have a CPM-D2 cutting edge.
Some traditional folders might also be good. You can't really go wrong with a Swiss Army Knife. The Victorinox Super Tinker or Compact are both offer a good amount of function without being bulky. The Sodbuster design is also a great work knife, and the ones by Case and Queen are good examples of those. The Case Peanut is a popular smaller knife.