These are the official websites for certain major programs. Just because 'your' program isn't here, doesn't mean it isn't major. These are just the programs in which I have an interest. Generally speaking, these programs are considered 'Systems-of-Systems' programs.

Major Defense Acquisition Programs
DoD site. Lists all programs that meet a budgetary level to qualify as a major program. 

Joint Tactical Radio System (JTRS)
Links to JTRS-related sites.

Future Combat System (FCS)
Links to FCS-related sites.

Deepwater
Links to Deepwater-related sites.