What are the best ways to make dorm beds more comfortable?

Target and Bed, Bath, and Beyond sell Twin XL mattress pads for under $30. Super cheap and really comfortable. Lots of pillows are a must too!

These stores also sell bed risers which will make your bed sit up a few inches higher, in effect providing you with plenty of under the bed storage. 

Everyone loves my dorm bed (which is usually hard as a rock) because I used one of those thick egg crate pads (http://www.campbound.com/cot-size-egg-crate-mattress-pad.aspx  for example) and then a mattress pad from target or bed bath and beyond, etc. It makes it really cushiony. 

My friend also uses a memory foam mattress pad and it works like a charm.

The memory foam mattress pads can be pretty expensive but sooo worth it!

Also, buying comfortable bedding and lots of pillows can really go a long way!