[bauer]

Nicely done. You could add in a mailing list to send users a digest of new or top vocabulary words every week.

[steelbird]

There's a subscription link at the bottom of https://buildmyvocab.com/

[galen211]

Second that - would also be interesting for English speakers learning a language like Chinese, where the average literate speaker can recognize about 5000 of the most frequently used characters.

[peterburkimsher]

galen - I'm making http://pingtype.github.io for learning Chinese! I don't think that studying characters is the most important thing though. Words are more important than individual characters! My program can help you type parts of a character, and put spaces between words automatically.