There are several for custom forms... you might consider Enterprise Forms (http://www.longnhi.com/) they have a good product and good support, though I'll be honest that we have a problem on our instance that as of yet they haven't been able to help figure out.  Use this link to get all the "forms" modules on SnowCovered and go through them yourself.

I haven't used any of the commercial project management pieces out there, so I can't comment on them.  However, I have seen in various posts around that Onyak support isn't that good.  I cannot speak from experience so my words are completely useless on that, but you may want to research that deeper to find out.

For project management/helpdesk, I actually wrote my own module (ported from a complete application I wrote a year ago, actually).  It isn't available commercially, though if there is enough demand I may go and revamp it to be less specific to my organizations needs and release it commercially.  Enterprise forms *could* be doctored into being used as a project management system, though that is not it's main intent so it would likely be lacking in that aspect.