Most of these have been mentioned already.
1/ 64 bit. Excellent to hear this is top priority.
2/ A conditional render output node. It would be great to isolate certain parts of a render for compositing, within the one scene. So if I want to isolate say the clouds, or set up a DOF pass, I could have the possibility to say to the node network, that this set of conditions only work for another output channel and have internal layers within the render node to set up what ever channel those conditions apply to. So say a scene camera is linked to a render output node, I would have within the internal network of that render node a set of user defined channel outputs (read seperate image renders and directory paths, with channel asigned numbers) which your conditional branches have directected to.
3/ Collate assets for a TGD. To make multi-machine rendering, and archiving completely painless.
4/ Multi object populations, which you generate to a cache file (also part of the collate project) saving on having to generate per frame or preview render, unless un-checked.
5/ Access to internal node settings from external node outputs. I'm thinking linear phasing to modulate those settings, ie sine functions to modulate noise position, or frame time to shift noise in y, would be good for wave animations, especialy if you could get loop'able noise functions. Got to say I love the noise effect in After Effects, it's a really powerful function, especially when you can link other instances to it. But, and edited to add, it would be bloody useful to have a distance shader control the sample quality within atmosphere and clouds, etc.
There you go, my five.
Cheers
Jon