Micro-investing is a form of investing that is really beginning to take-off, since it allows regular people to invest small amounts of money into a variety of businesses. Acorns for iPhone is a new app that could make micro-investing very easy. The way Acorns works is that it pulls data from your transactions and then lets you round-up your transactions to the nearest dollar amount. So, if you spend $59.50 on clothes, Acorn will let you micro-invest the other $0.50. Those micro-investments add up overtime but don't appear to be anything substantial on a transaction-by-transaction basis.
While setting up your account in Acorn for iPhone, you will provide your financial account details and investment goals. Then, you can decide if you want to be aggressive or conservative in your investing. That decision will determine what sort of businesses Acorn has your account investing in.
Manual micro-investments are possible as well, as long as you deposit money into your account.