What do you use for resource capacity tracking/forecasting?

Right now we send around a spreadsheet with a listing of projects and then the people attached to those projects and what percentage of their overall capacity will be needed for their part of that project (so they may appear under more than one project). I feel like there has got to be a more efficient way to do this. I was thinking of setting up a SharePoint collaborative SharePoint page with a spreadsheet built in so atleast there are no version issues, is there something better than that?