A thread on Highrankings today asked about available SEO project management applications that can help manage a wide variety SEO clients and projects. I had spent 6 months last year developing a web-based SEO project management tool that is currently being used internally by an SEO company. Unfortunately it's not currently available to the public. However there are some available tools out there that could help SEO's better manage their clients and ongoing projects.
One of the members Bernard, goes into detail about the various project management systems out there. He recommends that you need to "define the features that you require and then search for the package that addresses those needs". Now considering the following to define the type of application you need:
Critical Path / Critical Chain Scheduling - These are designed to define logic networks for planned tasks and produce time phased schedules for organizing/prioritizing the work. MS Project falls in this group.
Calendar Based Systems - These are calendar based task organizers like electronic versions of a Franklin Planner.
Collaboration Based Systems - These often resemble a mix of calendar based systems, a forum and a document management system. They are designed to allow a project team to coordinate projects where the scope of work is more fluid.
Once you define your type of software, try searching some of the available project management applications and directories with lists of those available.
http://www.web-based-software.com/ - Directory of Web-Based Project Management Software http://home.houston.rr.com/interplan/ - Comprehensive directory of windows based project management software http://www.basecamphq.com - Specific recommended web-based project management software