Something that I imagine should be widely needed is a Glow/Outline Object.
The basic idea of this Object is that it can apply a coloured outline to an object. This outline should have the ability to fade out (so as to look like a glow). Basic parameters should include range (how wide the glow/outline is), the colour and whether it fades to transparent or not.
This is currently not possible using HWA and pixel shaders because, according to the reliable source of Looki, the low limit of operations makes it an impossibility for PS 2.0.
Really, a sorely missed extension for anyone wanting a real time glow/outline. Anybody reckon they could hack one together?