The aptly named SummaryService summarizes text. The next time you get an overly long email that leaves you in the dark about its essential points, try auto-summarizing it. If it doesn't help at least it does no harm (and it's always interesting to see what a machine deems important).
Summarize a Long Email Message in Mac OS X Mail
To get a summary for a long email message in Mac OS X Mail:
- Highlight the complete message text or the portion you want to shorten.
- Select Mail | Services | Summarize from the menu.
Now, you can tweak the SummaryService's settings to fit your needs and save the summary to a text file.

