I have a folder called 'tools' on my localhost. In that folder I have PHP files which do general handy tasks like conversions, calculations etc.
I have one for urldecoding, which is simply echoing the $_GET variable. I just need to go to this url http://localhost/tools/urldecode?q=%5C and it outputs the correct character.
Using Opera (I think firefox has this too) I have shortcuts in my URL bar, like 'g something' goes to a google search page with 'something' as the search term. So all I need to do is put 'ud %5C' in the URL bar and voila.
It comes in handy quite alot. Examples are:
MD5 abc123 | e99a18c428cb38d5f260853678922e03
rr 'Hello (.*)' - 'Name: \\1' - 'Hello Bob' | Name: Bob
ud %5C | \\
sr localhost tools 3 | localhost tools localhost tools localhost tools