Can I just add that I started my son's Treasure Basket after reading this thread a month ago and it has been the best thing ever!
I got a basket with a few things together and offered it to him. He can't quite sit up on his own yet so I just propped him up with a couple of cushions and let him at it
Well, we haven't looked back since - it's become almost a daily ritual, and he now gets all excited when he sees me getting down the basket. He has his favourite items in there that he always plays with for longest, but he notices immediately if I add something new to the basket and pounces on that first.
And he'll now easily spend at least half an hour playing with the Treasure Basket, which I think is quite a long time for a 6 month old to be concentrating on something, particularly as there is no input from me, I just sit next to him and watch (well ok, occasionally he'll proudly hold up something he's found and look over at me and then I usually do say something like "oooh, wow, a wooden spoon, that's fantastic!").
Apart from being fun, another really nice thing about it has been that I can see a certain progression or development in how he's playing with the various items - he's becoming much more dextrous and involved.
So basically I just wanted to say that I can highly recommend doing it!