The Spyderco Dragonfly is a wonderful choice, it's small and often looked at as "cute" rather than "scary".
The great part about it is that there are so many choices!:
Spyderco Dragonfly Stainless Steel
Spyderco Dragonfly Tattoo
Spyderco Dragonfly 2 Black FRN
Spyderco Dragonfly 2 British Racing Green FRN in ZDP-189 Blade Steel.
Spyderco Dragonfly G-10 - Foliage green G-10 scales.
Others to look at, depending on how small you want to go are the Spyderco Ladybug(several flavors) or Spyderco Manbug(a few flavors). These are small and work well for the keychain but make awesome little EDC's as well.
Ladybug Options:
Purple
Foliage Green
Yellow - H1 Steel
Orange - H1 steel - County Comm Exclusive
Tan - H1 steel - County Comm Exclusive
British Racing Green - ZDP-189 Steel - FFG blade
Stainless Steel
Tattoo
Manbug Options:
Black FRN
British Racing Green - ZDP-189 Steel
Grey G-10 Sprint Run
There is also the Spyderco Jester Grey G-10 Sprint Run, I really like the blade shape of this one personally.
The Spyderco Spin is also a nice little knife, smaller than the Dragonfly, with a VG-10 Wharncliffe blade and Stainless Steel Frame Lock. You can find this with the Spyderweb pattern on the handle or the acid etched pattern. You can still pick them up for relatively cheap.
Depending on how much you want to spend, with it being a more expensive option, I'll throw out the Spyderco Gayle Bradley Air as well. It's around $150 US Dollars. Has nice silver twill glass fiber scales with the perfect amount of grip, milled titanium liners, 2.5" Wharncliffe blade in M4 super steel, doesn't have a clip and rides well in any pocket. This knife is just beautiful and has amazing quality. I couldn't be happier with mine and carry it in my watch pocket every day. It's more gentlemanly looking and won't scare people. It's just a great little knife.