I came across a site called Predator at the Chessboard which appears not to have been kept up to date but is still interesting. According to the author, a fellow named Ward Farnsworth, the site is what he calls a book that teaches chess tactics that you can read by clicking on the table of contents. One part allows you to quiz yourself on positions from the book. What I liked was his attempt to explain the basics of tactics in plain words as well as by example. Worth a look.
I’m disappointed there seems to be no sites for strategy similar to all those for tactics. You know, a site where you are presented with a position and asked to determine the correct strategy to employ. I understand why though…they are much harder to do. You have to do a lot of searching to find suitable games and positions, you can’t slap the position into an engine and get the right strategy, explaining strategical play requires more thought than simply declaring “White to mate in three.”, and so on. Probably the closest you can get are the various sites of US Life Master A.J. Goldsby. I suggest you check out some of his pages: