DND, I am more category/possibility oriented than upon anything specific. It's the surprise of discovering something you didn't know you had to try growing that is most of the fun in a seed exchange or swap for me. That said, I do love morning glories, as well as anything else that climbs. And then there are the tiny gems that clothe the ground beneath and "look back up at you" as a friend once used to say - some like Tellima grandiflora are major work-savers in impossibly shady, dry places - and some of that category have the delicacy of a fairy garden, like Epimedium grandiflora - but as Dan Hinckley pointed out, we've hardly begun to explore the world of epidediums - me included.
I guess, speaking for myself, when it comes down to specifics, a place is more of a point of departure than a point to occupy. Anyhoo, it's an attitude that makes my garden a little more adventurous than it otherwise might be - a mess yes, but an adventurous mess
Julie, is it okay to mention sources of seeds relative to your swap? I'll come back and delete this, if so - great source of unusual morning glories - http://www.ebay.com/sch/azurem...
There are other wonderful MG sources that others knowledgeable about the subject can recommend.