I used black chalkboard paint (I think I got it at Lowe's) on the wall beneath my kitchen bar. The kids were always putting their grubby hands on that wall and it looked nasty. I gave it two coats and it worked great. It applied jus like regular paint. I did it in an afternoon while my youngest was at Mother's Day Out (and I'm not remotely crafty).
Now occassionally I will "decorate" the wall myself for a holiday or something with the chalkboard markers and after they've dried for a few days it takes a Mr. Clean eraser to get them off - I'm fairly sure because of the texture of the wall underneath. The chalk itself usually comes off easily with a wet paper towel (again, I think if the wall was smooth it would come off easier dry - and I've never gone and gotten a chalkboard eraser). Also, one issue we have (minor in my opinion) is the chalk dust often ends up noticably on the floor. No big deal as it wipes up super-easy from our tile but I can only assume it would vaccuum just as easily from carpet. We have that whole wall done, it's been at least two years, and although it looks like a "used" chalkboard (yes, noticable tint of chalk left) it has held up great. I get tons of compliments and it is WAY better than the grubby wall we had before! I wouldn't hesitate to do it again!!
Edit: After reading the posts below I wanted to note that my youngest has accidentaly chalked on our "normal" wall next to the chalk wall once or twice and it wipes off just fine. Also, the paint I used was not magnetic.