Islamic investment

My coworker and I read an abstract today about Islamic investment funds. Oooh, they are impossible. Koranic law prohibits the charging of interest. All business arrangements have to be mutually beneficial to all parties and entered into them voluntarily. Then there are the underlying investments, which must follow 10,000 different rules. So complex, it seems impossible. Which is why there's only one very thinly traded Islamic ETF that we could find today, I guess.