As I announce here
https://plus.google.com/102337327214567011703/posts/frdLqYMu8H6
a new version of my visual assessment battery is out. For visual acuity you have as optotypes Landolt Cs, tumbling Es, Letters (ETDRS-type), gratings (only for low vision) etc. There's also contrast, and vernier, and faces. It's free: While fun to play with for anyone, to correctly apply and interpret, some optometric or ophthalmologic background is required.