Start a better dating website
From a business perspective, this is a need that won't go away EVER! That means there is a huge market and more and more people are using it to find dates. The problem with the current model is that it doesn't accurately reflect one of the best ways to meet people: through introductions.
Business Idea: Start a website that is based on introductions from friends and family.
The site would allow friends of single people and even single people themselves to build profiles not for themselves but for other people. That means you and I could add pictures, catalog likes and dislikes, etc to represent our single friends. We would network, connect and communicate with other people whose goals are to help their single friends find dates.
Why this works conceptually: We do this today. We try and hook up friends with people we know when we think there might be a good fit. We emphasis the features we think are most attractive while minimizing the less attractive features in an attempt to sell someone on our single friends and family members.
Challenges: You have to convince people who may never have previously had an interest in using a formal dating site to get online and start connecting with people with the express interest of helping a friend or family member find fulfilling relationships. On some level this lets people satisfy their curiosity about dating sites in a legitimate and productive way.
Business Model: Subscription or advertising.
Market: Business to consumer. The market is EVERYBODY.
Inspiration for this idea: A year or two ago my wife and I were interested in what our friend's online profile looked like. We signed up on the dating site to find out. That sparked my curiosity and I cataloged how the site worked from their revenue model to the things you could do without paying. I thought about the above business idea but never documented it. Just recently I came across a post by Paul Graham that reminded me of it so I decided to add it to my blog. You can view his post here: How to Start a Startup.