I am happy to announce that, after about 200 hours work, I have a chess engine that can occasionally play up to my crappy level (probably about 1300 USCF).
Here's the embarrassing truth:
-- Has only minimal eval (just piece tables and wood counting)
-- Only Alpha/Beta searches to depth 6 (no quiescent search yet)
-- 0x88 board representation
-- No move ordering
-- No hash tables
-- No checks for 3-fold or 50-move draws
-- Quasi-Winboard v1 compatible (meaning it has the bare minimum necessary to run in the Chessmaster GUI -- haven't tried any others)
-- Has no opening book or access to EGTBs
But it does know all the rules of chess, and move generation is not embarrassingly slow (perft 5 from initial position on a P4-3.0 takes 2.2 seconds and perft 6 takes 55 seconds).
At least it's good enough to beat me when I miss a Mate in 2, as shown here:
[Date "2009.2.22"]
[White "Myrddin Release"]
[Black "Merlin"]
[Result "1-0"]
1.b3 e5 2.c3 d5 3.e3 Nc6 4.Bb5 Bd7 5.Ne2 a6 6.Bxc6 Bxc6 7.Bb2 Nf6
8.d4 exd4 9.Nxd4 Qd7 10.f3 Bc5 11.Qe2 O-O 12.O-O Rfe8 13.Qf2 Bxd4
14.exd4 Re6 15.Qd2 Bb5 16.Rf2 Rae8 17.Na3 Re2 18.Rxe2 Rxe2 19.Qc1
Qe6 20.c4 dxc4 21.Bc3 cxb3 22.axb3 Qe3+ 23.Qxe3 Rxe3 24.Nxb5 axb5
25.Bd2 Rxb3 26.Ra8+ Ne8 27.Rxe8# 1-0
On a slightly more interesting vein, here's a draw in which I was actually surprised by a move or two:
[Date "2009.2.24"]
[White "Merlin"]
[Black "Myrddin Release"]
[Result "1/2-1/2"]
1.e4 d5 2.exd5 Qxd5 3.Nc3 Qe6+ 4.Qe2 Nf6 5.Qxe6 Bxe6 6.Nf3 Nc6
7.Bb5 O-O-O 8.Bxc6 bxc6 9.Ne5 Kb7 10.O-O h6 11.d3 g6 12.Be3 Bg7
13.Rfd1 Rhf8 14.h3 Nd5 15.Nxd5 cxd5 16.Nf3 Kc8 17.c3 a6 18.Bd4 Bf6
19.Bxf6 exf6 20.Nd4 c5 21.Nxe6 fxe6 22.Re1 e5 23.a3 a5 24.Rab1 h5
25.b4 axb4 26.axb4 d4 27.cxd4 cxd4 28.b5 g5 29.b6 g4 30.hxg4 hxg4
31.b7+ Kd7 32.Rb3 Rb8 33.Re4 Rg8 34.Kf1 Kc7 35.f3 gxf3 36.gxf3 Rxb7
37.Rxb7+ Kxb7 38.f4 Rf8 39.fxe5 fxe5+ 40.Ke2 Rf5 41.Rg4 Kc7 42.Rg7+
Kc8 43.Re7 Rg5 44.Kf3 Kd8 45.Re6 Kd7 46.Ra6 Kc7 47.Ke4 Kd7 48.Ra5
Kd6 49.Ra6+ Kd7 50.Ra5 Kd6 51.Ra6+ Kd7 1/2-1/2
And I'll admit I helped it towards the draw with 21.Nxd6.

I'm sure it will be months before I ever post anything further about it (if at all!). But I just figured it would be worth some amusement to all of you actual chess engine programmers out there.
Enjoy!
jm