One issue that arises is that many people are interested in effective philanthropy, but not yet ready to pledge 10% of their income, especially prior to securing a stable job (e.g. grad students). Personally, I've actually found it easier than expected, and am very happy that I made the pledge (as are all the others that I know of). But to accommodate those who aren't yet comfortable with that idea, GWWC: Princeton is also offering a 1% pledge that I'd like to encourage everyone to consider signing. (You don't have to be affiliated with Princeton in any way to sign or join our chapter.)
Why make a public pledge in this way? Two main reasons: (i) It may help motivate you to follow through if you make a public commitment like this, and (ii) the 'social norm' effect: your example might help encourage others to follow suit. So, please sign!
Having pledged to donate to the most effective charities, you may next wonder, which charities are those? GWWC offers some recommendations based on the World Heath Organization's cost-effectiveness research, but I think the single best resource to find proven-effective charitable organizations is GiveWell. You can donate direct to GiveWell, for re-granting to their top-rated charities, or (preferably) unrestricted so as to also support their ongoing research.
In related news, my birthday is coming up on Thursday, and anyone who wants to do a nice deed for the day can grant my 'birthday wish' by donating to GiveWell through that Facebook Causes link!