As is the case with any monthly budget, there's only so much you can do with it though. Unless the budget itself increases, there's only so much stretching to be done. And there's only three ways to increase your traffic budget: (1) get more from Google (SEM!), (2) better convert your Google traffic to traffic of your own (and I've said my piece there already) or (3) go find a new source of traffic.
Unless you're in the inner circle (again, Wikipedia, About.com), you can never grow to any significant size site inside the Google regulated industry. The regulator won't let you. Why would they? If they actually make you a big, important site than the balance of power actually starts to tip in your favor. No regulator likes that. Regulators make the rules, not the regulated.
Not so coincidentally, if you actually look at the recent successful sites over the past few years - YouTube, MySpace, Facebook, etc. - none of them got there by Google traffic. They created a product and figured out a way to get mass appeal outside the Google regulatory system. To make a bad analogy, if you were a global leader intent on world domination, would you make a plan to achieve this goal by working with the United Nations? No, you would go out and take what you thought was yours. That's what these big sites did. They flipped the virtual bird to Google and took what was theirs.
So here's where I'm going with this: despite all this, if you actually talk with lots of folks in the media industry, they're paralyzed by the fear of losing their Google traffic. I can't for the life of me figure out why though. Online revenues in media are still really, really small. Let's say you do do something to piss off Google and *poof* somehow lose all your Google traffic and accompanying revenue, then.....well, what? You've really lost nothing.
So it strikes me that the time is right to make some big bets. You can't make those within the system. My advice: start from scratch, take some chances in finding marketing channels outside the Google system. Be bold - make some bets while the upside is still very big and the downside is pretty small.
Cause the Google regulatory system is really a dictatorship - and like any dictatorship, at the end of the day, no matter what they say or do, the one who really owns everything is the dictator.