I have been writing an engine for the last couple of months, named TuxedoCat. Progress has been slow because I have a day job and other commitments but it has finally reached a point where it is somewhat usable so I thought I'd share it with the world! The project link is https://github.com/nfmccrina/tuxedocat.
It is a Winboard engine. It uses bitboards but no rotated bitboards or magics or anything. It has a legal move generator which has passed all the test positions listed on the chess programming wiki to depth 5 or 6 so I'm pretty confident it's correct, but I'm constantly haunted by the thought that there are obscure bugs which simply haven't surfaced yet. Currently the evaluation function simply counts material, and the search is a vanilla depth-first nega-max algorithm. The search is hard-coded to depth 4 because I haven't implemented a game clock yet so I want to make sure that it will make moves quickly. I've played a full game against the engine in Winboard (beating it soundly), though, so it is by some definition a complete product!
I expect the engine itself won't be of much interest to anyone here at this point because of how simple it is, but I figured I'd take the opportunity to introduce myself and acknowledge all the help I've gotten from poring through the archives of this and other forums, which has got me this far.