I am looking for a tighter integration between forums and email. i wanted to setup my drupal instalation to:
send an email to users when a new answer is posted to the topic
create a new node when users answer by email (optionally, to a mailgroup)
what are the best modules to do this? how would i accomplish this?
I would suggest you consider using the OG Mailinglist module, it is in alpha, but appears to do what you are looking for:
OG Mailinglist allows users to start new discussions by email and post comments on existing discussions by simply replying to emails. You get the best of both worlds: a browser-based discussion site and an email-based list.
There is also a good discussion here about some alternative ways to do it.
I'm the creator of OG Mailinglist and would be happy to answer any questions you might have. It is in alpha still but it's quite stable and in daily use by a community of 4-500 people at island.byu.edu
Also, if you want to have a look over at the code, the latest is at http://github.com/KyleAMathews/og_mailinglist