The d12 is a very under-represented die in D&D, so I'm always looking for more ways to incorporate it. One way that recently occurred to me was to use it for clerics' Turning Undead rolls, in place of the standard 2d6. Here's a comparison of the chances that a 3rd level cleric has of turning undead of various HD when using 2d6 or 1d12:
I'm pretty intrigued by the 1d12 spread. While the cleric is virtually guaranteed to turn 1HD undead when rolling 2d6, things are more iffy with a 1d12 roll. At the other end, the cleric stands a much better chance (in fact, his chances are doubled) against 5HD undead when rolling 1d12. So using 1d12 for Turning Undead has the effect of "flattening" the cleric's percentages, lowering his chances against lower HD undead and boosting them against higher HD undead. I may give this a try in my current Barrowmaze campaign and see how it works out in practice.