I've been thinking on what stoot mentioned about removing XP and replacing it with Imagination; if there was a straight 1:1 or even 400:1 conversion then we'll have a huge discrepancy between beginners and the level 60s. While some people might not see a problem with that (I'm one of those), it poses a psychological barrier for anyone new to Glitch. It's much like trying to enter EVE Online as a beginner without any guild to support you; frightening.
So I was thinking that getting XP to Imagination should be on the basis of decreasing returns, i.e you need to pay more XP for the same amount of Imagination as your total Imagination increases. To put it another way, XP to Imagination should have a built-in inflation. Example: Your 40 XP might be enough to buy 1 Imagination Point now, but your next Imagination Point would cost you 8% more XP, i.e. 40 for the first, then 43, then 47, 50, 54, 59... etc.
I dunno if I made sense there. I'm typing this in a hurry since I need to get back to work.