In Gmail, I have a number of accounts that I can choose to send from. (Old e-mail address, one used just for gaming, one for my blog, etc.)
How can I have a unique signature for each depending on which I choose?
Google just released Rich Text signatures, which also includes the ability to have a unique signature for each From address.
(I'm not seeing it yet, so I guess it's still rolling out.)
Update: After logging out and logging back in I'm now seeing the new setting. This is exactly what I wanted.
Have you looked at canned responses;
These can be used along with filters.
Hope this helps.