I think I just had a great idea.
It would be awesome if you could give your hands 1-5 star ratings, the same way you can do it with songs in iTunes. I mark many hands for review during play and later on some of them will turn out to be more important to review thoroughly (or repeatedly!) than others.
The process I'm thinking of is this: During play, mark hands normally. When you're reviewing hands and let's say you're only reviewing the hands you mark, you realize the problems you had in some of the hands you marked are easily solved. You still think those hands were worth marking and that they should stay marked. Now, if you could (in the replayer and PokerTracker in general), rate hands 1-5 stars, you could separate the tougher spots from the more standard spots and so on by filtering for or sorting by star rating.
Then, if you for instance filter to see which hands you considered to be 5 star hands 4 months ago, you can check if they have become any easier and if your understanding of these spots has improved. You can then change the rating accordingly.
Some people may also want to give stars depending on how awesome a bluff they pulled off in a given hand or whatever :)
Oh and I'm really sorry if this feature is already in PT4. I'm on a Mac and therefore haven't had the chance to use PT4 myself yet (anxiously waiting for the Mac beta!).
