Funny, here at OpenForce we're working on this specific problem. SDM and ticket tracker have a lot of overlap, but for internal system development, ticket tracker and BITS in general is your best bet. SDM is good for open-source development. Maybe one day SDM can take over and the unique system (as aD seems to be moving towards that with arsdigita.com/sdm).
BITS consists of /todo, /team, /new-ticket, and /notifications. Put together, they form a great organizational tool for in-house development. OpenForce supports multiple BITS installation already at various development projects, including some large companies.
