As the poster above me mentioned, there are many mutual funds and a good number of index funds geared specifically toward socially responsible investing. Even Vanguard has one, with the same low fees that Vanguard is known for.
All of my money with Vanguard is in VFTSX (up about 3.5% since summer of last year)
There are also entire companies which only sell funds of socially screened companies. After having looked through what criteria the use, I went with Calvert (one of the oldest of them), and have a couple of their funds. Their Alternative Energy Fund has done TERRIBLE, but my high-yield bond fund with them is up about 4% since last summer.
I also have an account with Lending Club, but instead of just using the filters and letting the system choose notes for me at random, I actually read and hand select who I will loan to, with an emphasis on things like home solar system purchases and other things I feel good (or at least neutral) about supporting.
I also have a few hand selected stocks I bought through Options House, but of course if (like me) you aren't extremely knowledgeable about both the ways of the markets and the individual companies, you may end up losing in capital than you ever gain in dividends. Its a risk I'm willing to take to avoid helping out companies like Monsanto (and of course many, many others!)
As of right this second it looks like I'm down, but then again, the entire market took a nose dive today, which means its time to buy!