There is certainly a number of applications that constantly scans the screen eg. the game tables, offering real time percentages for anything you might think, winning percentage, push/fold situations etc.
That is mostly, screen grabbing then computing the images grabbed with pre-grabbed images to find out what the current screen says. This can translate from community cards to stack sizes to active players in table.
I myself developed such a program not while ago that could grab the community cards, then compute me a percentage of winning based on my hold cards.
Things can't be really more complex since serious applications (like Pokerstars) don't give any other information, except their log files but that's legal to utilize eg. Pokertracker uses these logs files, doesn't do any really complex stuff like DLL injection and such.
Restricted apps like, say, Texas Calculatem do exactly this etc. screen grabbing+. Older SNG Wizard version (newer ones are supported) had a mechanism where one could create a scenario for push/fold where Pokerstars didn't liked. I didn't found it on newer versions.
In short, if an application goes the screen grabbing way and calculate real-time statistics is probably considered cheat.
You referred bots. These aren't so different by the way, they do exactly the same thing, although some AHK mechanism is in order to make them behave like humans. They're also considered cheat since they're basically AHK + screen grabbing application.
Personally i don't think they're worth the effort and $$. The information you get from them they can really be learnt.