Fred Wilson’s 10 Golden Principles of Successful Web Apps (He’s at Union Square Ventures and has a blog) This is a summary of the talk he gave at Future of Web Apps Conference

Speed — it just has to work fast

Instant Utility

Voice — attitude, style, personality, you should feel like your consuming media (CNN, Fox News) when you’re interacting

Less Is More — Great services are simple. Example: delicious (which drives our “what we’re reading” section). You can do very little but still be powerful.

Programmable — APIs, read/write APIs, Absolutely essential to let others contribute functionality to your application.

Personal — Avatars, Backgrounds, UGC, so people can feel ownership

“RESTful” — Everything in the application has a url. And the url has clean and understandable path. This way the web can access your app in deep ways. Build on an open architecture.

Discoverable — Build from the ground up to be discoverable through google, but also through Social Media. Build from the ground up to be viral. So it can push itself.

Clean — The app has to be simple visually, not busy on the page. Lots of space. Big fonts. Not too much functionality per page. Very inviting. Tumblr is a great example you just know what to do.

Playful — Have fun. The ability to play in an application. Foster a game dynamic. Like Weight watchers, you establish goals, you get points and report against goals, you meet goals and are rewarded.