Like Basecamp, Unfuddle is also an online project management tool that allows users to perform all the standard project management tasks, ranging from bugs and issue tracking, team collaboration and communication, task assignment etc. It also contains a web based repository browser.
Trello is another simple to use and extremely efficient web-based software project management tool. Owing to its ease of use, this one is my personal favorite. You can add different status boards, perform task assignment, and add role assignment and can perform all the other standard project management activities in a very short span of time.
TeamGantt is another amazing software project management tool and is extremely ideal for projects that involve large teams