What are all the possible business models that can be used on the web?

Apart from advertising and SaaS, could you provide a list of all possible other business models (regardless of the type of business it is).

If you're just looking for a list, professor Michael Rappa wrote a detailed paper listing all the models he could find on the web at the time. It's a long but good read.

Here are a few applied models that I could think of:

Offer aggregation (ex: Kayak)
By listing prices from merchants around the web, it saves customers time from comparison shopping manually by visiting each of the merchants' websites.

Daily deals (ex: Groupon, Woot)
Groupon took the one deal per day model that Woot was using and added the concept of "tipping point" -- whereby a certain number of people have to buy the deal for it to be activated.

Just in time (ex: Dell)
This was first developed by Toyota in the 60s. The core idea being to keep parts inventory always on-hand so that they could custom build PCs quickly and ship them out.

Growth first (ex: Amazon)
Since Amazon's start, the plan was to postpone taking profits from the business and keep reinvesting it to grow. Bezos had earned plenty of critics for this approach but his model eventually paid off.

Lifestyle takeover (ex: Google, Apple)
While they both started with a single product, their core interest to growth is you. By trying to provide you a whole ecosystem of any interaction you'd have with technology, they've created a brand you can't avoid interacting with on some level.

One place for everything (ex: Walmart, Amazon)
By having everything under the sun with large scale distribution, they can compete on price which drew in the masses.

P2P (ex: Kickstarter, Etsy, Gumroad)
Personal, one-on-one transactions.

Answer: as many as there are stars in the sky.

Do some research - a good book to get would be "Business Model Generation" and learn how people define their business model based on the opportunity they are targeting.