Many individuals have used Bitcoin purely as an investment vehicle, treating it similarly to a commodity to exchange. Like any other volatile investment, this has had mixed results, but as a whole the value of a bitcoin is up about 300% of where it was 2 years ago.
Just in the last year, some bitcoin companies have started to get the attention of silicon valley investors. Most notably, Coinbase has raised over $6 million with such backers as Y Combinator and the FundersClub, among others. Similarly, CoinLab of Seattle, WA and has raised over $500k from their investors including, but not limited to Lightspeed Ventures.
Recently a group of angel investors have come together to form BitAngels, a bitcoin focused investors group looking to bring small startups on to the main stage.