There are the top 5 most popular project management software (based on Alexa rank):
2. Zoho Projects
4. Central Desktop
There are actually a lot of project management software aside from mentioned above and it's confusing which ones to use. The best way to choose which one would be best for you it to read reviews and compare the various software.
Here's a blog that compares project management software from each other: http://www.timedoctor.com/blog/2011/...e-alternatives
It also has a short review of each software for you to have an idea about them.