I'm trying to think of potential logos at the moment, and I guess it has to be something synonymous with Joachim's tennis style... I found a couple of sites on Runes, and they've got Jera, which apparently means success (second pic) and tyr, meaning victory, which was apparently seen in war times
anyway, just an idea. Not exactly something to be put onto t-shirts, but it could be an example of a logo / letterhead etc. Time to put the thinking caps on!