If you are looking into build a family tree, from scratch, this can be a pretty daunting task. Instead of tracking the information yourself, you can create a tree on Geni (for free) and have other family members help build it for you.

Getting started is pretty self-explanitory, you can either create the tree as you know it, browse the existing last names to see if yours is listed or import a GEDCOM file.

Personally, I have never created a family tree but I would be interested to hear what others use when trying to create one.