It's not in every account, but "Server Clipboard" is an intriguing addition to Google Docs. It bypasses browser problems with copying and pasting, and lets you copy multiple items and paste them — in Docs, for now, and probably Gmail soon.
One of the Google Operating System blog's readers reported in on finding the Server Clipboard icon on his Google Docs toolbar and, lo and behold, I found it in mine, too. It adds a feature that advanced desktop text editors have long bragged about to the online workspace, and it's pretty convenient in offering both plain text and HTML pastes of everything you copy. It also removes a niggling problem with trying to use Google Docs' own copy and paste in a browser like Firefox, that doesn't offer access to your computer's clipboard (but probably for good reason).
It's a convenient little trick in Docs for now, but if Google makes it available across their whole suite — Gmail, Calendar, Reader, the whole shebang — it'd be a really useful tool.
Server Clipboard in Google Docs [Google Operating System]