in the last few wweks I discovered some very interesting mutt patches, that might be interesting for other users also. the first one adds header caching for maildirs resulting in massive improvements reading large maildirs. http://wwwcip.informatik.uni-erlangen.de/~sithglan/mutt the second patch adds an gui-like sidebar to mutt (result is http://gallery.blackwing.de/screenshots/mutt_pane?full=1). patch is available via: http://vorlon.cwru.edu/~jrh29/patch-1.5.4.jrh.sidebar.8
Thanks for the suggestions. I added the maildir header caching patch to mutt-1.5.6-r1, but I left out the sidebar patch, simply because it's so intrusive and seems like it will be hard to maintain.