Cast at Conventions?

Probably a dumb question, but is there a unified resource, link or site that let’s us know when a cast or crew member is attending a convention?

One place I could check to see which convention (when and where) cast might be attending (in a dream world it would also tell me in advance if I can get signatures, or pics with them, etc).

I’m reminded of meeting Joel years ago at Retro Con in Pennsylvania. I only found out about it by chance and would totally have missed that opportunity had I not been working a vendor’s table there.

@Lesley, if this doesn’t exist, do you think that might be something that could be folded into announcements?