Here are our shelves for Lolly (three and a quarter) and Snail. I recently went through them and got rid of a lot of stuff as they were collecting crap [by crap I mean awesome toys] and here's what we have out now, post purge. These are Lolly's:
Lauri tall stacker blocks, not a lot of use of these to build upwards as yet, but lots of wand and stick building, leading to dog thumping.
Lolly is crazy about numbers at the moment, so I've got a collection of number activities, a foam puzzle, number cards, and a set of wooden numbers.
Here are Snail's shelves:
Spinning top, switch adapted bubble machine, drums and bells, her musical whacking toy (lol), her collection of toys that make a sound when you squish 'em, and her cars. I'd say her squishing toys and her whacking toy is popular here (when she is interactive).
We also scored this great road table from a friend (it doesn't fit in her house), so we're using it as a loaner. Lolly is loving this for garage play and train building!