Rumplo is a very nice community driven t-shirt collection with voting, profiles etc. Good filtering functionality by color, and nice combination of popular and upcoming on the front page. Sort of Digg for t-shirts
Duck With Glasses is a collection of t-shirt links and images, mostly affiliate driven, with some search features. If you know about the big t-shirt companies there is not a lot of new stuff here.
Both of the sites here that are primarily collections of affiliate links are ok, but if they wanted to be really successful I would suggest they build a widget that t-shirt bloggers could put in there side bar using their own affiliate codes, that way the blogger gets a bit of revenue and the directory can have an link built into the widget back to the main directory. Anyone trying to use affiliate links know what a frikin nightmare it is to try and build those links, and if you could automate the process (as they are already doing) I think bloggers would be all over it. In fact, build it to work for any affiliate products and millions of bloggers might take advantage, think about all those incoming links
As Rangga from the DailyTee.com I missed out Tfodder.com which IMHO is certainly one of the strongest designs. Looks like the site was put together by Deft Creative out of the UK so kudos to them, not sure if they did it as an experiment, portfolio piece or for a client? I wonder if they could help me redesign and add some features tcritic