There are currently 275 puds on this site, divided into 4 groups of different size. All puds are playable, although I disagree with the choice of resources for a number of them. These are usually older puds, created with 1 or 2 players in mind.
Most 1 player maps are probably best played in an unpatched version of the Battlenet Edition of Warcraft II, or the DOS version. This is firstly because most of these maps were made for the DOS version, before the Battlenet Edition came out, and secondly because the Battlenet Edition got many updates that were aimed at multiplayer games, and were breaking the intended behaviour of single player maps.
32 x 32 Puds
64 x 64 Puds
96 x 96 Puds
128 x 128 Puds