Many of the swag ideas shared are fantastic. To go one step further, I suggest co-branded swag:
I love my Marketo drink bottles and fitbit - I always like to see things I'm actually going to use. So +1000 to socks, laptop sleeves and munchkin plushies
I'm using a travel mug from my previous company. A Marketo one would be much welcomed.
Regarding the call for laptop stickers, I would seriously recommend vinyl decal that can be removed and reused.