Andrei Zmievski posted a cool little blog entry on how to get Firefox to parse a mutli-line URL. This tip is very handy when cutting and pasting URLs from an e-mail or from a message board where the URL spans multiple lines.
Here's another Mozilla/Firefox tip: if you copy a URL wrapped over multiple lines from somewhere and try to paste it into the address bar, you will end up only with the first line of it. To fix it, go to about:config and change editor.singleLine.pasteNewlines setting to 3 or add:user_pref("editor.singleLine.pasteNewlines", 3);
to your user.js file. Now all the line breaks will be removed upon pasting.
This has always been a big pain in the arse. In the past I've always ended up having to open up a text editor, paste the URL and then strip out the new lines. This will be a real time saver!