Clickz reports that in March the top 50 online advertisers spent an estimated $419 million dollars. Thats a big number, especially considering it leaves out all of the other online advertisers and omits things like affiliate advertising spend.

E-book marketing, arbitrage, and search engine spamming are hot topics for people looking to make money online. Want to own a real asset that consistantly throws cash at you every day? Build or buy a real content web site. Even better if you can find a deal, get a generic domain name with guaranteed traffic.

There was once a time where you had to invest big dollars to create a television station, newspaper, or magazine, to recieve media advertising dollars. Not anymore. Anyone with a basic understanding of web site publishing can own a sliver of media with a global audience. You don’t even need a sales team to sell your adspace — just use Google Adsense.

A few interesting observations — January’s top 2 advertisers, LendingTree, and Lowermybills are nowhere to be seen on March’s top 50. Vonage too has disappeared. IAC/InterActiveCorp, the parent company of Ask.com is number one. (This top 50 list in February was only $272 million — that means March saw around a 150% increase. Could there be a bubble emerging?)

There is no question, today online media is king. Despite all of these ad dollars, there is even more money flowing online from spending consumers. Don’t limit yourself.