All very trial and error, problem with the pub posters is weighting, i.e. more people see the posters in the pub they go to and vote for it so you're essentially building up the popularity of that pub.
The tshirts were good too but they were for the right audience, it's getting the right target market is the key, facebook apps is one I'm having a look at now, only takes two seconds for a user to add a new app etc.