World of Solitaire - Over 50 beautiful free web based Solitaire games. Klondike, Spider, FreeCell and more.
Sage Solitaire - A new twist on solitaire from the maker of SpellTower
PySolFC - PySolFC is a collection of more than 1000 solitaire card games. It is a fork of PySol Solitaire.
Solitaire Lounge - Solitaire Lounge is a spin-off for the classical game of Solitaire with amazing animated themes.
Churchill Solitaire - The most diabolical version of solitaire ever devised. Played by Sir Winston himself. Available via the AppStore and Google.
Solitaire.gg - Massive open-source solitaire project with hundreds of games.