Simple things first:
1. Path Simplification - esp. on expanded Strokes | since my first post (AD v1.3) highlighted the problems with it.
2. Textbox Linking (perhaps more a Publisher feature but would be handy here too - remember Aldus/Macromedia Freehand?!)
3. Perspective Grid
4. Photoshop/Illustrator swatch / palette converter?!
More complicated (i think)
1. A 3D Rotation tool... | for instance to rotate / correct perspective / on a text layer or vector group.
No extrusion (looks always awful), just z-depth, perspective and rotation
2. Clever curves, curve/spline & handle interaction?! For a lack of examples: like: Astute Graphics VectorScribe / InkScribe