The best Android DAISY reader that supports DAISY 2 (the format used in CALS) we’ve found so far is Darwin Reader, which is a little pricey at $14.95, though the demo version works just fine for testing purposes. There are a couple of other other options that we've had less success with:

• GoRead, which directly supports Bookshare books, but is limited to DAISY 3 and won't play most NNELS titles.
• There is an Open source Daisy Reader app as well, which is worth keeping an eye on.

If you have any experience with these or other apps, your feedback would be welcome.