Inspired by zooids post in another thread. I've created a pair of scripts that allow round-trip linking between OmniFocus and Mail.
The pair of scripts here allow you:
• to create OmniFocus actions from messages in Apple Mail
• jump from linked OmniFocus actions back to the Mail message.
Download:
the most recent version is available here
Installation
1. Copy the Add OmniFocus Action script into the folder:
~/Library/Scripts/Applications/Mail
creating the folder(s) if necessary.
2. Copy the Open Linked Mail Message script into the folder:
~/Library/Scripts/Applications/OmniFocus
creating the folder(s) if necessary.
3. Add the Scripts menu to your menu bar if you haven't already by opening the AppleScript Utility, located in Applications/AppleScript/, and selecting the “Show Script Menu in menu bar” checkbox. The menu should appear on the right side of the menu bar.
Running
When running Mail, the Add OmniFocus Action item should appear in the scripts menu. Select a message in Mail, then run the script. You should find a new action in your OmniFocus Inbox awaiting a context and project designation.
When running OmniFocus, the Open Linked Mail Message item should appear in the scripts menu. Select a linked action in OmniFocus, then run the script. The mail message should open.
Disclaimer
I haven't tested the scripts with IMAP accounts. OmniFocus is still in alpha testing, so the scripts may break at any time. I suspect that I'll continue to use and maintain them until the Omni Group provides built-in support, so I'm likely to maintain the scripts for awhile at least.