We used to have a similar thread in the old forum, but is a list of the plugins I can't do without, and the links to them. Thanks to everyone involved.

Bunyip's Attributes Controller
Chemo's Ultimate SEO URLs
Langer's Easypopulate
Marge's Ask a Product Question
Sales Report
Tim's Image Handler
Merlin's Cross Sell
Portali's Quick Updates
Dr Byte's CSS Flyout Menu
Reesy's Info at a Glance
Recover Cart Sales