Combinational Motifs by Blokh is pretty good.
Know any good tactics study guides?

well if you are ok using the computer then tactics trainer? you already have diamond membership. virtually endless tactics problems.
I wish tactics trainer would allow you to select specific tactics problems to work on. For example, if I find I am continually losing to forks, I might want to brush up on my forks. As is, it throws mostly checkmate combinations at me, it seems.
It would be nice if computer training included more tactics as well.

You might try to get hold of the Encyclopedia of Chess Middlegames. Each chapter is on a particular theme...pins....forks....etc. The book has over 1700 positions taken from actual games. I used to wonder why i never got combinational positions and after i studied this book i began to get combinational positions all the time. Of course they have always been there....I just never saw them until i studied this book. The book is put out by Batsford and may or may not still be in print, but if it is it is well worth getting. Chess Combination as a Fine Art is another book worth having. Paperback with over 300 positions. Test Your Chess I.Q. is another good book. 1290 positions in which you are given a certain amount of time for each position and get a "rating" based on your results. I got these books long ago...don't know if they are still in print but if so they will certainly help improve your chess vision. Chess Tactics for Intermediate Players is a computer disk with hundreds of positions arranged by theme. You are given a certain amount of time to solve the position and you are given an ELO rating based on how well you do. Put out by Convekta...this is a wonderful disk for those wishing to improve their tactics.

I wish tactics trainer would allow you to select specific tactics problems to work on. For example, if I find I am continually losing to forks, I might want to brush up on my forks. As is, it throws mostly checkmate combinations at me, it seems.
It would be nice if computer training included more tactics as well.
I wonder if something like this link might be what you're looking for.
Hi. I am interested in studying up on tactics. Does anyone have any good ideas for books that rely mostly on diagrams and or computer programs that might help?
Thanks.
I see that you have premium membership here, so unlimited access to TT. Well, then why not use it? It's one of the best (if not the best) tactic trainers available. I don't quite see the point of studying tactics classified after the motif you use (like fork, X-ray and so on). In a real game you don't have this information.

Convekta have brought out some easier level versions of their excellent CT-Art.
Think these softwares do what you're looking for.

"I don't quite see the point of studying tactics classified after the motif you use (like fork, X-ray and so on). In a real game you don't have this information."
I think the idea is to practice areas of your game you know you are deficient in so that when they come up during a game you stand a better chance of seeing the tactic, of being on the lookout for it, and being able to execute it when it does appear in front of you.

I use both Tactics Trainer here and www.chesstempo.com. I am not aware of anything better than chesstempo, but I'm always interested in hearing what others use to improve their tactics - book or internet.
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Hi. I am interested in studying up on tactics. Does anyone have any good ideas for books that rely mostly on diagrams and or computer programs that might help?
Thanks.