Chris, your question falls a bit off the 'Type Identification' activity of this forum. Without giving us an idea of the look you want, how do you think we can help? My suggestion is to check out DaFonts, or TypeNow.net and don't limit yourself to things with chalk in the name. What you probably want are simple hand-printed fonts. Put it as white on green or black and it looks like chalk most of the time.

Of course there are better things if you want to buy them, depending on the look you want.

Eraser Dust is the most common Chalk Font

several of the glyphs are really hard to look
at ... for example, the R.

http://www.agfamonotype.com/isv/cat_display.asp?type=dis15b

There's also Letraset's Chalkline Bold - a commercial font as well.

One could argue that Comic Sans and its Mac counterpart Chalkboard
could pass for chalk fonts. And they're both free.