How do you help a friend who's in the dumps?

What are some tips on helping someone else build their self-esteem up? I have a friend whose parents have always put her down, even telling her 'how stupid' she is all the time. They basically set her up for failure, then put her down when she fails at something (well, 'fails' in their opinion, anyway). She has a hard time believing in herself and her abilities, but she's a wonderful person.
What can I do to help her see this about herself?

How old is she? & if she's under 18 she can go to social services I think.. and by the way don't call them ' PARENTS ' its more like strangers with cold hearts.. get at me in comments or fun mail..

She's over 18 now, but the way they treat her still affects her life. True, they definitely don't act like 'parents' should.

Reminds me of my grandparents..they put me down for years and I still can't bounce back... it hurts but I learned to live past it and use it as fuel for motivation to be successful.. usually people like her tend to be successful in the future look at Oprah's life..wasn't any better but look at her now..why she doesn't get with a friend and rent an apt. and work then go to college?