A great link (a collaborative DB) for educational technology related conferences. The site also lets you see different views of the data (chronological, geographical, list all).
http://edtechevents.dabbledb.com/publish/educatonaltechnologyconferencecalendar/821fc54f-0c3e-46ca-8681-3a46fd592c72/mainlisting.html?embed=true
If you know of some not listed, just add it in.
-Joel G.