A Few Mini-Reviews
Chess Tactics for Beginners - This is a great "first" collection of about 1,300 tactics problems. It is a few levels of difficulty below CT-ART and I would highly recommend it for use in "circles training" before moving on to CT-ART. It has a good mix of mates, material-winning problems, and drawing problems. There are four or five "mistakes" where there is a better move than the "solution," but all-in-all it is a very high-quality collection. It keeps track of your solving accuracy and assigns you a rating to help track your progress. Finally, it has several features that I made heavy use of such as the ability to mirror the position, reverse colors, or view the board from white's perspective even when it is black to move. I found that randomizing the positions in this way helped to further solidify the patterns in my memory. If you buy this program, make sure that you download the patch from the support section of ChessOK's website.
Advanced Chess School - While I did get some benefit out of this program, I wasn't terribly impressed with it and can't in all honesty recommend it. The translation of the explanations is terrible and often doesn't make sense. Also, there is a very high number of composed mate studies that are frustratingly difficult and which I'm not sure were very beneficial to my improvement. It's not strictly a tactics collection as there are also a number of opening-type problems as well as quite a few strategy motifs. I'll likely return to this program at a later date and see if I get more benefit when I'm a stronger player.
Personal Chess Trainer 2.0 - I'm currently halfway through the Tactics Modules in this program. It consists of 4,320 tactics problems, 1,440 endgame problems, and 720 strategy problems (which each give a short explanation of the solution.) The tactics problems have a fairly high ratio of mates (as opposed to material-winning problems) although that improves as you get into the later modules. I've generally found it to be a good choice for a follow-up to Chess Tactics for Beginners. It is very well suited for "circles training" because that is the methodology that the program uses to train you. The first time you see a certain tactics problem you get three minutes to solve it. The next few times you get a minute and a half, then a minute, then 45 seconds, and finally 30 seconds. You end up repeating each problem about ten or eleven times during the course of a module. So essentially you do ten circles and it's all automated. It keeps track of the time you spend on each unit and then further breaks it down into average time per problem. It also automatically repeats any problems that you miss. In short, I'd highly recommend this program. If you haven't yet purchased it though, you might wait a month or two for the new version to come out. It is supposed to fix some mistakes and oversights as well as add an opening section.
Chess Position Trainer - This is essentially a database designed to store and train you on your personal opening repertoire. Not only is it free, but I've found it to be one of the best programs out there for this purpose. It allows you to break up your repertoire into multiple sub-repertoires for easier organization and training. It has a very large number of configurable options for drilling you on your openings. You can also download user-made repertoires from the site. I use the Dan Heisman recommendation of adding one new move to my repertoire per game. After a game, I look up the opening to find where we went out of book, figure out what the book move was, and add it to CPT. I then drill my openings with the training features until I can play them in my sleep. Highly recommended...did I mention that it's free? Version 4 should hopefully be out soon (the current version has some problems with Windows Vista.)
Silman's Complete Endgame Course - I absolutely LOVE this book! It's practical, concise, and easy to understand. The decision to divide the material by rating is brilliant...I can't believe that it's never been done before. There are enough diagrams to go through the material without a board, but I tend to go back and play through the positions against Fritz after reading through a section. I find that helps to burn the information into place better. I'd say that this is likely the ONLY endgame book that you'll need until at least the expert level. I can't recommend it enough. Even if you aren't a big fan of Silman in general, you owe it to yourself to take a look at this book!
Chess Endgames 1 - This program is put out by Chessbase and authored by Karsten Müller. I really enjoy the video training format that Chessbase uses. I've found this to be a good companion to the Silman book. It plugs a few holes that Silman doesn't cover, such as the Knight & Bishop Mate. I know, I know, I know...I'll probably never run into it, but if I do, I'll be ready! It also gives a slightly different perspective on the overlapping material. I've found that learning the same idea/concept/technique in more than one way helps me to remember it even better. I wouldn't say that this is a "must have" like the Silman book is, but if you've got the extra money laying around and want to further solidify your endgame technique, I'd say that the Chess Endgames series from Chessbase is a good way to go (there are four in the series so far: Basic Knowledge for Beginners, Rook Endgames, Major Piece Endgames, and Strategic Endgames.)
I can't give much of a recommendation here since I've only been through a book and a half so far (although I've got a large number of books on my wishlist.) I can recommend the two that I'm familiar with though: Chernev's Logical Chess is a great first game collection book. Every single move is give an explanation. It is a little dated and has a few analysis errors, but I still think that it is a good place to start. The games are great and the explanations do a good job of helping to understand what is happening. His follow-up The Most Instructive Games of Chess Ever Played is also highly recommended (I'm about halfway through it.) It's a step higher in terms of audience skill level (I should also note that it's in descriptive notation.) It doesn't have an explanation after every single move, but still has plenty of commentary when necessary. The selection of games is also both exciting and varied. So far I've thoroughly enjoyed it.
That covers most of the products that I've used so far. I'll try to do mini-reviews anytime I get something new. I hope it helps!!!