I just love the Sennheiser PX200 headphnes. They're light, have an excellent bass response and they can be folded for ease of carrying. They also come with a nice case for storage.
The headphones are light when worn, don't dig into your ears like some other headphones and also don't cause a problem if you have long hair. They are also fully adjustable - there's a metallic headband - none of the cheap think plastic stuff.
Prices start from as little as Â£20. For more information, check out my review for this product on www.ciao.co.uk
under the username patwanet
Hope that helps.