The three ascetic disciplines of Lent are praying, fasting, and almsgiving; if you still haven't decided where to donate for Lent, besides your local charities you could perhaps consider one or both of these two organizations:
(1) Catholic Relief Services, which is collecting money to help people in the aftermath of the Japan earthquake. CRS has an AIP grade of A.
(2) African Windmill Project. This organization helps farmers to increase yields and consistency in Malawi, which repeatedly has problems with famine. Chris Adare gives a taste of some of the projects for this charity on the African Windmill Project blog.