I was thinking "web based" a little while ago and still need to do that. But I couldn't find anything that suited my requirements. One of those requirements is that each client be assigned a unique email address, ie: firstname.lastname@example.org contacts support and our reply is sent as fred-blogs-site-com@mySite.com so that we know instantly which user is trying to poison the well. My other requirement is that the app be coded in Classic ASP so I may have to write that one myself.
I have all the bits and just need to integrate them when I have some spare time (currently have a couple of projects close to completion).