gmail – Issue Tracking / Case Management that integrates well with Google Apps

I’m looking for a way to track issues (not particularly software bugs, but rather general issues) where I’d like to be able to create a case/ticket for each issue and then link in google docs as well as gmail conversations (

Is there something in the google suite of apps that can be used for this purpose? If not, what tools can link to google and allow this (especially the linking in of gmail conversations)?