MathMagic features a tiling puzzle. Patrick Hamlyn has been using his amazing polyomino solver to find many solutions here, but I still managed to find some things by hand first. (Last month on the chess puzzle I failed to contribute anything at all until near the end of the month when I proved 3 of the unsolved cases unsolvable.)
Ponder This has yet another abstract game between two players to find the best strategy for. I have not tried solving it yet.
The solutions to Puzzle-Up are out. I had so many unsolved that I didn't even bother sending answers in. I reached a point where it seemed all my remaining ones needed leads ultimately from the letter-change-and-transpose ladder and I was stuck with a wrong path there through linen-Elgin-Glenn (and too many other possibilities for the rest of the path).
The Australian CISRA puzzles will mostly not be out until April, but the first round is available now. B.1 Artefact seems to be stumping everybody.
A puzzle contest in Kingdom of Loathing (which seems to not have any KoL-specific nature, in the parts seen so far, except using their forum to get hints and submit answers) has been stumping everybody.