SEGA Swirl(site info)
Puzzle game for PC and SEGA Dreamcast. Connect and remove similar colored swirls. Users can play by themselves, with up to 4 players, or over email.
http://www.SegaSwirl.com
3.
ADC-Soft - Games(site info)
Shareware and freeware puzzle games for Windows. B-Jigsaw and B-Puzzle allow making your own jigsaw and sliding puzzles from BMP and JPEG files, CTris2000 Tetris variation, Hex Mines Minesweeper variation.
http://www.adcsoft.com/