Texas Calculate 'Em is allowed on Stars. I played around with it before I actually started playing on Stars so I couldn't take advantage of the 'Auto-Read' that it offers. (at the time, it would only auto-read Stars tables - other sites you needed to manually enter the information)
Well, manually entering it was a pain in the ass because it would take so long. I watched a video some guy put together to push his affiliate link site showing how Caclulate 'em will help you win money hand over fist. It's rather amusing. If you download and install Party Poker through his link and play 20 hands, you get Calculate 'Em for free. The really funny part is that he plays on PokerStars to demonstrate the program.
The program itself does a few different things: it gives you your odds of catching your outs, the number of outs you have, as well as making a recommendation on what you should do. These 'recommendations' are something else...The guy ('zbutler') who made the video pretty much ignores the recommendations and does his own thing based on the information provided with Calculate 'Em. The demo shows him playing a $6 Turbo SNG which he does win, but at one point he donked off a TON of chips. It made me wonder how many times he had to shoot this demo so he won.
In short, it IS a neat program, but I don't think it gives anything to anyone that has any experience at all playing. Most of things it gives you are things you probably already have calculated: # outs/ percent to win/ etc. The only thing it does is do it automatically and allow your brain to do something else.