For some really well-drawn, original games (simplistic gameplay, but I think that makes them fun and lighthearted - besides, what do you want from a Flash game?), there's http://www.orisinal.com
A couple other good ones I've played are http://www.ferryhalim.com/orisinal/g3/bauns.htm and http://www.ferryhalim.com/orisinal/g3/bells.htm (apropos of winter time). Honestly, most of them are really worthwhile.