Should give you some ideas, the active users widget changes behaviour based on where it is displayed, if its inside a topic it shows the poster in that topic, if its inside a category it shows recent posters in that category etc. widget.area.url gives the url of the page the widget is in.
Latest users widget
Not sure why we haven't added this before but here it goes
Added it to our homepage as well. You can set how many users you want to display in the widget ACP.
Now we just need to add the "What's Going On" widget, and we'll be back to the 1990s