I've not tried any of them myself, but the list in the article from http://news.ycombinator.com/item?id=1134301 seemed quite sensible.

Give them something to love.

do things 'the right way'. high standards are my personal favorite motivation for doing a good job and working harder. if i know the quality of my work matters i will try harder to get it right. in some orgs it seems quality is completely disregarded in favor of 'just getting things done' and respect for the job suffers.