I'm finding more and more need to cram rich functionality into tiny boxes for widgets, mobile phones etc. Anyone finding the same? Any good references to get up to speed with current best practice?

Got any specific examples of what you mean, Phil?

Things like this: http://www.google.com.au/ig/directory?hl=en&root=%2Fig&dpos=top&num=24&url=http://www.google.com/ig/modules/reader.xml&q=reader&start=0

But I am finding myself working on even more functionality in that small space. Why? Because there seems to be a trend to give users the tools they want/need for THEIR OWN sites and not to expect them to come to yours.

 Another example is the various embedded video players - Brightcove being a very rich one. 

What seems to be working for users is what is simple for them to do themselves, without asking for help or needing documentation. The best widgets I'm seeing are the simplest.

Thx Chris - that is really useful... I like the one about not using valuable real estate for advertising!