Repurpose
Take a service or approach applied to one market, and apply it to another.
Examples: Chill (Turntable.fm), Yammer (social networks for businesses)

Digitize
Take content or functionality that exists only in a legacy form and put it online or in an app.
Examples: Dr. Chrono (medical records), Google Books

Automate
Take a task that seems tedious and currently requires humans and automate it away.
Examples: Google (search rankings), EffectCheck (emotional impact analysis)

Unify
Create a common platform that ties together proprietary solutions or providers.
Examples: Twilio (abstracts away carrier-specific APIs), Greplin (single search engine for lots of services)

Componentize
Take a piece of functionality that people currently implement themselves and make it a reusable component.
Examples: Apigee (APIs), Get Satisfaction (support forums)

Connect
Transform a situation where people are isolated or lonely by connecting them in a novel way.
Examples: Facebook, Meetup, LetsLunch

Catalyze
Encourage people in a community to generate data that would otherwise be less structured or available.
Examples: StackOverflow (programming Q/A), reddit (social news), Curvio (IMDB for products and apparel)

800 subscribers @ $10/mo.

"Here’s another way to come up with startup ideas: walk around your house or apartment, and look for “hot spots.” A hotspot can be an area of high information density, clutter, stress, disorganization, or any place that has a suboptimal solution. Then think about a web or cloud solution to that hot spot. Let’s take a look at a few examples:

Music CDs -> iTunes, Amazon MP3 store, doubleTwist, MP3tunes, etc.
Bookshelf -> Amazon, Kindle, iBooks
Stereo system -> Sonos, Squeezebox, Rhapsody, Pandora, last.fm, Spotify, Grooveshark, MOG, Rdio, etc.
External hard drives -> Amazon Simple Storage Service (S3), Pogoplug"