Over time in dotnetnuke we've gone through a number of different pieces of bug tracking software, and had ups and downs with most of them. At the minute we've settled on Gemini from Countersoft, and after having used it for a number of months, its dealt with most of our needs. If you don't know it, it's worth checking out, particularly as it offers a free 10 user licence. If you're involved in an open source project or a .net community website, they also offer free licences. Check out their licensing @ http://www.countersoft.com/Licensing.aspx