1 - First section of this (1a) is an improvement:

move the 'Refresh every x minutes' setting to the main Fast Dial preferences... or at least have it there too, and allow people to override it on each bookmark if they wish.

The way I use it, I would very much like Fast Dial to update all of my sites @ every 30 mins.

Main part of this (1b)...

Have Fast Dial update the images according to the settings whether Fast Dial tab is open or not... not sure how easy this is... or if it already does it?

2 - Rollover image previews

It would be great to get a bigger image preview when you rollover the thumbnails. Reason for this, is the question... do I want to visit that website? Although I love the thumbnails and the usability of Fast Dial, I can't answer that question by looking only at the thumbnails. If there was an image preview, then there's a chance I could see images and news / article headlines, and that would help me make that choice.

I feel the two things combined... the whole lot of images updated according to a global setting (or the overriden ones), followed by the ability to get a more readable snapshot of the site, would really aid the appeal of the app.

To such a degree that I might try to fit a javascript image preview mod in myself... ! I think this would be killer.

Anton