[bcl]

The masking characters need to be more similar to the characters being typed. eg. ll is easily readable with letters like nrs, etc. in the background.

[umbrae]

This is a good thought - I had implemented character set matching (uppers to uppers, numbers, etc) before, but I worried that it made it almost too hard to read for the user.

You'll notice that I'm only using lowercase letters currently - that was an intentional choice as it seemed too obscured when using a fuller character set.

I'll give this another look though and see if there may be a good middle ground.

[jf]

I agree, it's pretty easy to read the text if you zoom in on the field: http://skitch.com/joelf/bayjs/halfmask