Real-time poker tools

I've noticed some programs that appear to read cards from online games and provide odds calculations and stats in real-time. They have names like PokerIndicator, PokerAdvantage, and so on. Surprisingly, I haven't been able to find any discussion about them online, just a lot of ads. (For example, type "poker odds" into Google. Somebody's paying to get to the top of those Adwords.)

Has anybody used these or know anything about them? I'm curious to know how well they work, whether they're useful, whether the poker sites try to thwart them, and so on.