Maybe you've been needing the right excuse to splurge a little, or you've been saving lots of errands for the weekend. Well, on Saturday, your retail therapy could benefit a good cause. A few enterprising folks at San Francisco's Seeing Labs and Mission Motors have come together to form Shop for Japan, a global fundraiser that benefits disaster relief charities in Japan, which takes place on Saturday.

There are lots of local businesses joining the effort Just look for the poster at right in local shop windows or type in your zip code over at Shop For Japan's map. A percentage of each business' revenue will go to a charity of their choice.

The organizers are utilizing social media tools to recruit businesses and shoppers. Businesses who want to participate in the event can sign up through Facebook, where they can get the word out to their supporters and download customizable posters to display in their shop windows, and shoppers are encouraged to spread the word on Facebook and Twitter and upload photos from the event on Shop for Japan's Facebook and Flickr pages.