You lucky fellows with normal ears have no idea how fortunate you are.
I have mishapen ears of some sorts and ipod buds as well as many others I've tried just dont stay in even when I'm just sitting down forget about running. What works for me is some type of where they either wrap behind the ear or clip on. You should just be able to make a trip to bestbuy or futureshop or whatever and find something of good enough quality for 20$.
Wow! I am not the only one this happens to? I swear to everything holy I cannot keep buds in place to save my life. Just like you, even sitting still the slip and end up sounding muffled. So here I sit all geeky with this mini Ipod Shuffle and around head headphones sticking out.