Bucking the trend of “Get big, then figure out how to monetize” these startups had solid business models from day one which weren’t mainly based on advertising.

Originally launched with the name Mollyguard, Eventbrite is an online event registration service that provides organizers of events with inexpensive, easy to use tools to make planning an event a cinch. Makes money on payment processing.

Mint.com is a free online personal finance service that is aimed at being “easy and secure way to manage and save money online.” The service is accessible anywhere, anytime over the web.
Makes money with affiliate sales.

Wufoo is an Internet application that helps anybody build amazing online forms. When you design a form with Wufoo, it automatically builds the database, backend and scripts needed to make collecting and understanding your data easy, fast and fun.
Makes money on subscriptions.

Threadless is a user-designed, user-submitted t-shirt web company. That means that they take users submissions for t-shirt designs, pay the designers for their work, and sell their t-shirts on the web.
Makes money on t-shirt sales.

Box.net provides over 1.4M users with secure online file storage and sharing functionality. They say their platform “allows personal and commercial content to be accessible, sharable, and storable in any format from anywhere.”
Makes money on subscription fees.

Woot.com pioneered the “one deal per day” business model that is now used by several sites across the internet. The basic idea is that only one product is available for sale at any given time and each product is only available for 24 hours.
Makes money on product sales.