I'm thinking of replacing the icons on my WHMCS installation. Does anyone have a idea where I can get nice looking icons from, or any designer recommendation here who can do a custom set?

Try Danish Royalty Free (http://jonas.seph.ws/stuff/drf.zip)
Example: <<removed URL>>

or

Fatcow Hosting Icons (http://www.fatcow.com/free-icons/)

A nice, free icon set that can be used for whmcs is Coquette (http://dryicons.com/free-icons/preview/coquette-icons-set/).

<<removed URL>>

A excellent website is one called Iconfinder (http://www.iconfinder.net/). I have acquired many icons through their site and they're all great!

You may want to try www.graphicriver.net

Its the best site for icons and other graphic resources.

Dom

graphicdriver.net is cheap and highly recommended. ;)

iconfinder.net

Basically your best friend if you do not want to spend money.

As some of the above posts, I suggest 'Iconfinder'