I collect a few things...
2003 SP Authentic Marcus Trufant Patches, think I have 55 or so
2007 Exquisite Regular and Spectrum Jordan Palmer, probably have 60 of these
Kyle Boller, just super rare, I already have the 'everyday' stuff, if you have some of these, I have plenty of paypal
Ladies line...this is a fairly new thing for me, mostly Olympians, McKayla Maroney, Shawn Johnson, Natalie Coughlin, Jennie Finch, and then Michelle Beadle, hey, at least she covers the Olympics...
the past 4+ years my collection has been very profitable to the point where each year I add more autographs and paypal to my bank account, while buying whatever I want for PC...I try not to spend too much on any single card, but when I have money and nothing to do, what the hell...
by trade im a lot buster on eBay...not uncommon to drop up to $1000 in a weekend buying cards to flip...with ebay constantly doing free listings, I try to stay well stocked...at the start of the year I had like 3500 autos, 1500 SP Authentic RCs, and then like 1500 assorted rc/inserts from various brands...if I can keep turbolister from crashing, I should have around 8000 cards listed...