The Pbs Kids activities corresponding with the series Elinor Wonders Why provide a number of language targets and are another example of modern web design (i.e. not flash-based). I also like activities with outdoor themes that you can couple with small "field trips" of your own if working in-person. These are now added to the PBS Kids task-analysis spreadsheet.

Curious Campout- good narrative play, like a mini "Toca Life." Click to interact with objects e.g. to set up the tents or put wood on the fire.

Hide and Seek- for one or two players (one covers eyes), hide 4 characters across a wooded area and take turns finding them. Good for spatial concepts and causals, as players are more hidden with clothes colors that camouflage them. 

Two more are added to the linked spreadsheet above!