Bohemica has been on hiatus for a while. But moves are afoot to bring it back. In the meantime, you can get the revised version of The Yellow Pages of the Czech Language: Grammar and Usage for Learners. More details will soon appear on http://grammar.czechly.com.
You can also download Czech Language in Context, a free e-book I created from Czech-related pages on Wikipedia. It would make good reading for students who want more in depth information about the language.