* Contribute something like IMAP IDLE for "git fetch".
Inboxes (and any git repos) can be kept up-to-date without
relying on polling.
+
+* Expose targeted reindexing of individual messages.
+ Sometimes an indexing bug only affects a handful of messages,
+ so it's not worth the trouble of doing a full reindex.
+
+* code repository integration (with cgit, gitweb, etc...)