The key here is that you're exchanging something relatively easy for you to produce in exchange for something that's relatively difficult for you to do but relatively easy for someone else to do. Not a big upfront commitment, i.e. a job or contract.

It's generally hard to be an expert at it all: back-end, front-end, design & UX. Is there a place for people to barter their services? If there isn't, maybe there should be ;)

Related (also posted on Quora): http://www.quora.com/Is-there-a-place-where-back-front-end-developers-designers-trade-work