I'm working on a software app that I will sell online. I'm going to go with the "release-early, iterate quickly" plan, so rapid customer feedback is all-important.
I'm looking for a web app for my site that can handle any or most of the following: forums, feature suggestions, bug reporting, voting on features, release notes, mailing list.
I'm just starting off so I don't need something enterprise level - just something to get the momentum going.
http://uservoice.com/ is what you want. There is a free version that allows 100 voters and 1 forum. Once you need more then that you can upgrade accordingly. But this is great as a start.
I'm not sure there's one tool for 100% of the above. For example, there's UV and GS as suggested here but they're useless for release management.
Which is fine! Just know that you'll have to piece together a few things.
FYI since others have avoided "releases," I suggest a blog -- easy to post updates and easy for your customers to subscribe via RSS or email as well as search an archive.
Same with a mailing list -- consider having that just be "your blog with comments." If you want lots of discussion on the mailing list, use forums instead -- it does the same thing but Google will index it, etc..
http://uservoice.com for the front end
http://batchblue.com to manage leads
http://outright.com to track their revenue to the bottom line
Google Analytics to see which pages are getting hit.
Kiss Metrics to be able to easily ask users what they want.
Uservoice.com is good for Q&A forums. It'll save you a bundle in support costs.
Use a wiki for registered users. It will provide them a way to capture knowledge which your product or documentation didn't make easy or obvious.