When in Safari, Mac OS X is smart enough to copy the formatting of text when you copy it from a webpage. Unfortunately, this is not always convenient. For example, say I wanted to copy a link to send to my friend via IM. When I try to paste the link, instead of pasting the URL, it pastes the anchor tag. Also, let's say you are trying to type a paper with some word processor and you want to quote some webpage, but you need the text to match the font and styling of your paper. Microsoft Word offers an ambiguously named Paste Special that removes the formatting from text, but not all programs have that (although it would make a very nice addition to the Services menu.)
Fortunately I have found a quick solution to this problem, which I have been using for over a year. After copying your text in Safari, simply change focus to the Google search bar (Command-Option-F) or URL bar (Command-L), then execute Paste, Select All, and finally Cut. This can be done very quickly from the keyboard by holding Command and typing V-A-X, so this doesn't take a significant amount of time once you get used to it. Then end result is text with no formatting.
This still seems to work reliably even with huge amounts of text: I tried to paste pi to the millionth digit into the Google search bar as a test. Text selection within the bar became dreadfully slow, but when I cut it and then pasted it into TextEdit, all of the text came through properly, with all of the formatting stripped.
[robg adds: You might also look for a 'Paste and Match Style' option in the destination program. If it exists, this usually has the keyboard shortcut of Shift-Command-Option-V. But for apps that insist on pasting with style, this is a pretty quick workaround.]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20051213055833832