Omni
2010-01-07, 01:30 PM
Mac OS 10.5 (I believe) added support for mail-message URLs; on those versions of the OS, the clip-o-tron adds a link back to the message to the note field.
Since I sync my OmniFocus database to my phone, I let Mail be the archive/filing cabnet for my messages, and use that link to bounce back to them as needed from OmniFocus...