Swag is not limited to t-shirts and tote bags. There's an entire industry out there devoted to making people smile at conferences (or making their kids smile when they get home).
In 2006, Drew made up some hot/cool travel mugs on his own; they were well-received, and turned a nice profit for the PSF.
[insert other swag items from years past here]
Lead times for swag are similar to those for shirts.
Other ideas for swag items:
Python brand cut-to-length bungee cords: http://www.kk.org/cooltools/archives/001250.php