Kershaw Leek, my personal gateway knife.
The Ontario Rat 2, the Esee Zancudo, Brous Bionic, Boker Pipsqueak, a bunch of Sanrenmu knives, most Case or other traditional slipjoint knives, Strider PT, several automatics by ProTech, Microtech, and others. Don't forget Chris Reeve's small Sebenza and Mnandi, if your budget allows.
Benchmade Mini Grip, 530, 531, Mini Bone Collector (I have the one with a D2 blade and walnut scales).
Spyderco Delica, Dragonfly, Ladybug, Manbug, Chaparral, Native, Chicago, Pingo, UKPK, Techno, Leafstorm, Chubby, Memory, Air, Ambitious, etc.
More Kershaw than I care to count, including the Shuffle, Nura, Cryo, and even a couple of the Emerson collaborations.
Other than 0900, Zero Tolerance doesn't make anything that small.
Honestly, three inches is a sweet spot for folders. Your choices are vast.