Just a brief reminder in this, our forum for sharing treats and wisdoms: that my underused office inside the Central Nexus does include some hand-made resources for anyone hunting ideas or inspiration! Pay a visit either by using the 'lift' teleporter in the Nexus' lobby or direct teleport and you'll find links to resources in-world and off it.
If you just want to hop straight to things here and now, you can find all the appropriate feeds at Building Extropia, which is also perhaps your main resource. There's my del.icio.us collection and a Google Reader highlights page for all things Extropian that come across my path.
That's wonderful stuff, Cral! Quite inspiring. I simply adorethis poster, for Mars. I dare say I've seen work like this before, though. Amy Kate Martin has assembled some posters in a similar vein, this time more focused on the sciences in general than on space travel. Not as retro, mind you.