I have a soft spot for one button jump running type games ala Canabalt. Remember Edmus? That was the last productivity killer for me. Now I've stumbled across Go Go Agent Zero, which isn't really as good as the afore-mentioned titles, but really does have a cool sensation of speed. And explosions. Lots of explosions.
There is the sense, when playing Go Go Agent Zero, that you have very little control over proceedings - but I still had a decent amount of fun. Switching into different vehicles has literally no effect on proceedings but, for some reason, I loved jumping off the edge of cliffs onto speedboats, motorbikes and cars. It made me feel cool.
So yeah, Go Go Agent Zero. It will make you feel cool.
Go Go Agent Zero [Kongregate]