Today I received an e-mail with a long story, awfully ugly formatted HTML with multiple linefeeds, that I wanted to clean up. I didn't feel like downloading an application that could do the work, nor did I want to clean it up manually. Then I got the idea to use the Summary Service (SummaryService.app), and set the value to 100%. That way I get an unformatted text block (no HTML), without multiple linefeeds. Fast and easy.
[robg adds: To use the Summary Service, select some text in a Services-menu-aware application such as Mail or TextEdit, then choose the Summarize option within that application's Services menu (under the application's name). When the new window opens with your text, move the slider below the window to 100% to see the whole text block.]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20041206101612546