This Excel 2010 spreadsheet lists over 200 genre-specific conventions. It includes URLs, locations, and what kind of activities they have.
Note that this was assembled for use for authors, artists, and musical performers. There are quite a few one-day listings that are really comic book sales events that I didn’t include.
If you have an update or a convention that I missed, please let me know and I’ll include it.
The latest version is 1.0 (Initial release, 7/1/2013)