yes, you can get your visa in any chinease consulate. It takes about a week. There are a few types of visa's: single entry, double entry and multiple entry.
THey have increasing cost so figure out how many times you plan on going to China in the next 6 months and you"re all set. THe only thing is that you have to drop it off an pick it up form the same consulate. Although they might be able to mail it back to you, I don't remember that being an option.

Enjoy

BTW, HK and mainland china are seperate so if you plan on going into HK and coming back to mainland, that counts as 2 entires..