Try http://www.phplinkdirectory.com/ for a very good free open source link directory with loads of features.
thanks for the suggestions lads i'm giving http://linkmachine.net/ a go for a week as someone recommended it to me recently, and will check the other suggestions out depending on how it works out. was very simple to install, seems quite straightforward, integrates nicely too.
PHPLD without a doubt. I converted to it from another script a few months ago and its amazing. Does everything you need, plus more Great community to help out with any questions or problems so you can't lose!
If I get his name right, Duncan Carver? Has an excellent free directory script. It is pretty indepth but very powerfull if you want to set it up so. Brad