The most popular search-for-a-cause service is GoodSearch. Powered by Yahoo, it will send half its ad earnings--about a penny for each Internet lookup you make--to your pick of 37,000 nonprofit groups and schools. You can also add its toolbar to your browser. Nearly 100 new recipients are added each day, said co-founder Ken Ramberg, who hopes GoodSearch will become one of the top 10 search engines by next year. The service sent several hundred thousand dollars to various charities in 2006. Each nonprofit group receives a check at the end of the year once users have rung up at least $20 in its name.