ORCA Digital net every Tuesday evening.
There is a Western Digital Net every Thursday.
Good place to get hooked on digital modes using FLDIGI or D780 from Ham Radio Deluxe.
The MOST complete description of digital mode identification I have seen in one place. Includes audio snippets.
sigidwiki.com Amateur Radio – Signal Identification Wiki
From Mark Holt W7EAZ
Artemis: Desktop Radio Signal Identification Software is another Great software option