There are literally hundreds of ways to make money on the web, unfortunately all require either, time patience, effort or some level of expertise.
The obvious one is adsense
If you love researching and writing come naturally to you adsense is a great way to earn money online.
That said you do need to have patience and learn about markets, competition, search engine optimization and marketing.
Though if you get the recipe right, work hard and am patient you soon build a solid port folio of work which can bring you a reasonably consistent income.
Another is stock market investing and trading, although some might not see this as making money from the internet, you do predominately use the internet for trading using online trading platforms and to research company's to trade and invest in.
I like to call the stock market as a 'force multiplier' I make money from a small hobby business 'fixing computer' and from online marketing 'adsense' and then use that money to trade and invest on the stock market.
Build websites, there's a great website called flippa where you can sell a built website. Obviously the more effort you put into the site in the form of marketing and SEO the more you will get for you created webpage.
I have an online lady friend that almost makes a whole second income from selling developed websites on flippa.
Commission based sales, you can create a blog and sell other people's stuff on it on a commission basis, look at clickbank, commission junction even amazon.
You can find freelance work by contract as a writer, copywriter and all sorts of jobs. Of course this depends on what type of work your familiar with, but online contract work is a great way to make a quick buck although like any job you need to perform.
Ebay selling, although hosts of people are doing this and it is very competitive these days there are still opportunities to make good money on ebay. It pays to have reliable connections overseas and have some start up money but you would be amazed at what people buy off ebay!
Hope I have given you some ideas!