Places to get project ideas:
Other Science Fairs:
Greater Philadelphia Homeschool Science Fair - This is a separate fair that does not serve as an entry point to the CCSRC. It takes place on a later weekend, and has lots of fun workshops during the day. In addition, the handbook (available online) for this fair offers lots of helpful information about doing a science fair project.
Chester County Science Research Competition - This is the competition sponsored by the CCIU that qualifies students for the Delaware Valley Science Fair.  Students must qualify by competing in their school science fair (or, for homeschoolers, in the CCHS science fair).
Delaware Valley Science Fairs - A few students from this fair continue on to the ISEF fair.  To compete here, you must first qualify in a regional fair.  For Chester County residents, that means in the CCSRC. 
Intel International Science and Engineering Fair - This is the "big" one.  A few students from the DVSF qualify to compete here.