I've been to three shops that had their menus on chalkboards and every time I tell my partner that we should do that too.I don't know why some do and some don't,but my guess would be to keep people from stealing,or changing the worlds aroundLetter boards are also more expensive,and you have to keep up with them.Chalkboards are easier and convenient,and they give that MomandPop feeling to the shop.You can also change the prices with the swipe of a rag 8) mr.esp.
we use chalk boards for all our menu boards, you are right it fits into the image of a coffee house. it makes it easy to change and explain the menu and looks less corporate. we painted our own chalk board for the last store 12' wide
Muddy Cup is right. In my shops I always left a section, if not the whole board( of the sidewalk A-frame), for the opener to "express" themselves in what ever manner they wanted(within reason)...cartoons, trite quotes, Haiku whatever.
Had lots of customers come by just to check out what we had to say that day and the employees loved it..stimulated lots of good conversations/arguments....but you have to get a whitty opener and it helped that my shops were located on or near a University that was more or less liberal or was not turned off by others opinions. Election years were always lots of fun round here especially since Bush was in Austin. One of the most memorable read: "Vote for Bush! Get him the Hell out of Austin". Sombody later ripped the quote and printed up bumper stickers. Go a bit of free press out of it too. Have fun with it.
you paint the permanent things on the board...logo, drink names, etc and leave blank spots for prices or anything else you may want to change. Actually using chalk on the whole board is usualy pretty hard to see and in C.Shops there are always fluids flying everywhere. A runny sign looks very bad...people think you lack the ability to clean which is why whiteboards are moe or less useless...can't get em wet