In issue 117 (the latest I've received) of 3d World mag, they have a great article on "ten sketchup" plugins.
The best looking one looks like it allows push/pull of curved surfaces. Pretty sweet.
I'm about to try them out!
Here's the top 5 on the list:
1. Extended Push/Pull: tinyurl.com/ruby-joint
2. Easy Multicurve Surfaces: tensile-structures.de
3. Better Bevelling: tinyurl.com/ruby-sketchy & tinyurl.com/ruby-round
4. Add SubD Modelling: smustard.com ($22)
5. Tools on non-planar surfaces: tinyurl.com/ruby-tools