Sorry I didn’t get back to you earlier - I ended up trying to sort a 18gb file at work (475 million rows) and it took forever, so I left it, went home and cooked dinner (roast sirloin, Jersey Benne potatoes and stir-fried vegetables, with a bottle of rosĂ© from Langedoc). Lucky I had 60gb of free space on the network work drive.
Anyway, here’s what I use when I want to give myself a bit of extra space: http://delocalizer.mac.findmysoft.com/
It was written for OS X 10.2, but I can confirm that it still works fine in 10.6. Except for one game: Spore. If you have that, copy the application to an extra drive, run Delocalizer and bring it back again.
It goes through each application on your main drive and gets rid of the selected language portions, and as I said can save you many megabytes. It may give you some breathing room.
Oh, BTW, your link is broken…
PS There’s also CleanMyMac. I haven’t tried it and don’t know about its efficacy.