I went to a seminar given by Mark Cleghorn on creative uses of photoshop for photographers yesterday. It was excellent value for money, but there was an awful lot to take in. I really must experiment more with photoshop rather than just cropping and adjusting levels which is mostly what I use it for now.
Bob Campbell from OnOne software demonstrated their Plugin Suite 4.5 for photoshop which is capable of some jaw-dropping stuff, Plugin Suite 5 is due out next month and is a big step up apparently.
The latest Adobe Camera Raw can do an awful lot more than I realised as well.