Alpheios is a plug-in for Firefox that shows on-demand glossing and grammatical data for ancient texts.
Memrise is another memorization website (like Quia, Quizlet, or Anki). What makes this one unique is the ability to create your own mnemonics or other ways to remember information.
The Packard Humanities Institute (PHI) has released its canon of Classical Latin authors online. It also includes concordances of words.
The Digital Classicist Wiki includes many resources, tools, and online projects related to Classics. A great place to browse and see what’s out there.
Luke Henderson discusses his use of active Latin in the classroom and shows an impressive feature film (in Latin!) created by his students.
Marvel at some wonderfully preserved gladiator mosaics from Bad Kreuznach, Germany.