Thats very nice. I was able to do most endgames in the first try except the Vancura position, i failed to do it right a few times. Good to refresh my endgame knowledge here :)
In some positions the computer sometimes moves just back and forth for a while. An avoid-threefold-repetition mechanism could be added here.
Here are some more interesting Pawn ending positions, from chapter 1 and 2 of 'Chess Endgame Training' by Bernd Rosen. If you are interested i post more.
4k3/8/4K3/4P3/8/8/8/8 w - - 0 1
White wins (opposition is irrelevant when the pawn is on the sixth rank already and king is in front of pawn)
8/4k3/4P3/3K4/8/8/8/8 b - - 0 1
Black draws (defending king has to stay on the file of the pawn)
8/2p5/8/1k1P4/8/K7/8/8 w - - 0 1
White draws (sacrifice pawn in order to reach drawn endgame using opposition)
6k1/8/5P2/8/5PK1/8/8/8 b - - 0 1
White wins (sacrifice pawn in order to win the opposition - not the only win)
4k3/8/8/8/8/1P6/8/2K5 w - - 0 1
White wins (key squares)
8/3p4/8/2P5/P3k3/8/8/7K w - - 0 1
White wins (Square rule: block the route of the black king with a pawn sac)
8/8/1p6/p1p5/P1P5/1P4k1/2K5/8 b - - 0 1
Black wins (Opposition)
8/2k5/8/8/6pP/6P1/5K2/8 b - - 0 1
Black draws (Opposition)
2k5/8/p1P5/P2K4/8/8/8/8 w - - 0 1
White wins (another triangulation example - more than one solution)
K7/8/p7/8/8/2k5/P7/8 w - - 0 1
White draws (another example of the reti motif)
8/8/8/5p1k/7P/6K1/6P1/8 w - - 0 1
White wins (win the pawn without letting the black king enter)
8/p4K2/P7/8/8/8/1k6/8 w - - 0 1
White wins (the bodycheck method)
8/8/k1p1K3/2P5/8/8/8/8 w - - 0 1
White wins (drive the black king away from his pawn)
8/8/8/4p1p1/8/5P2/3k2K1/8 w - - 0 1
White draws (another opposition example)
8/8/6p1/1k6/4K3/8/5P2/8 w - - 0 1
White wins (another bodycheck example)
8/8/8/8/8/P4p2/k6K/8 w - - 0 1
White wins (the anti-reti study)
8/8/8/8/k7/P1P2p1K/1P6/8 b - - 0 1
Black draws (another example of the reti motif)
6k1/8/3K2p1/8/6P1/8/8/8 w - - 0 1
White wins (the Zig Zag manoevre)
6K1/8/6k1/8/8/p7/P7/8 w - - 0 1
White draws (unusual King move)
8/8/7k/8/1p6/7K/2P5/8 w - - 0 1
White wins (another unusual king move)
2K5/k7/7p/8/8/8/6P1/8 w - - 0 1
White wins (the queen of bodycheck studies, very difficult)
You can check these endgames with
http://www.shredderchess.com/online-chess/online-databases/endgame-database.html