While "Kakatuv" as a website is not very interactive, it has been an invaluable resource for me as an educator. It has collected nearly every prayer and presents them in a legible PDF format along with transliteration and translation. Students who are just learning to read Hebrew have benefited a lot from this resource.
Each set is a group of trope in a common pattern one would find in the Hebrew bible. They include music notation and audio. Click on a link to launch the lesson in a new window. MP3s and practice sheets can be found on the downloads page.
If you're looking for an iPad app set up in a similar way, check out "PocketTorah Trope."
G-dcast is a student-friendly website that includes short, fun, informative animated videos on lots of Jewish topics, including holidays, the parsha of the week, and Talmud.