(I don't quite get it...this looks like a repost of an exact same post, so I figured I'd reply here too, since it looks to be the same post...sorry:
Hands down it has to be the Web Help Desk Software:
http://www.webhelpdesk.com/ We needed a customer web portal, an faq knowledge base for self-help (to get them off our backs), customizable ticket form submission with custom fields and customizable ticket categories, email-to-ticket conversion, auto-ticket routing to our techs based on skill-set, customer satisfaction surveys, escalations, reporting, service level agreements with alerts, track time spent on tickets (and report on them), and most importantly, it had to look professional, as it is forward facing to our customers
...and not look like we brewed it up in a day. (we also wanted to run it on a mac os x server, and it does! Win and Linux installers too; don't let the mac bit scare most of you
;) We got it all with WHD! Couldn't be happier. We looked at their Free Edition but it is only for one support agent. The Lite Edition may fit your needs, but we need to track computer and software assets, which was not avail in the Lite Edition. They have stellar support and the UI looks totally "enterprise" and less "spreadsheet-like" vs. most of the open source and php digs out there. Again, couldn't be happier! Worth a peak!
:) T