If you have a twitter account and American Express card:
You can donate $10 (I think they get about $7 after fees) to Mesifta Tiferes Yerushalayim (MTJ) for free.
All you have to do is Sync your American Express card with your twitter account by clicking:
Then tweet the message #AmexTFF10 to get $10 back on next $10+ purchase in Lower Manhattan below 23rd street (Zip codes: 10011, 10014, 10012, 10013, 10008, 10006, 10004, 10005, 10038, 10002, 10009, 10003, 10010) (QtyLtd, Exp 4/29).
You can then check for a confirmation by clicking on @connect in twitter (top left of screen) and then clicking on "Mentions"
Then call MTJ at 212-964-2830.and ask them to process your Amex card for $10 before 4/29.
You can sync one Amex card per twitter account.