Ok, I've found a decent list, here are the secret achievements. Note that all of the structures must be on the map at once to gain the award (you can't build 14, demolish one, then build another).
Hot Dogs Fan: Build 15 hot dog stands
protected by fredley♦ Mar 2 '13 at 1:09
Thank you for your interest in this question. Because it has attracted low-quality answers, posting an answer now requires 10 reputation on this site.
Would you like to answer one of these unanswered questions instead?