I find myself using delicious.com more and more (yes, I was a very late joiner). I read so many random blogs and articles and always feel bad when I forget where I got an idea from. I have been using delicious as a reference to my brain, the tagging system makes things really easy to recall. But the thing that always gets in my way is their tagging system, space delimited. Since delicious only accepts “spaces” rather than commas, I was frustrated one day to find duplicates of some of my tags:

And no, there is no such thing as "ui,"
I couldn’t imagine myself being the only one with this issue, 5 seconds of Googling uncovered this 3 year old thread about the problem. My usual greasemonkey disclaimer applies (I love delicious, and I allowed 3 years for this to be fixed, so I will make a patch if people choose to use it). So, better late than never, this one is for you @stowboyd!
Install the GreaseMonkey Script Here