Neither eBay nor Craigslist "need" ads. In fact I've never even seen a third-party ad on eBay. They only showcase their own 'ads' and listings. And eBay has a 25% stake in Craigslist, so that place can afford to run perpetually gratis if management wanted it to. I do notice they have some text ads.

Google advertising brings in huge money. Just look at how much some people make using adsense (Engadget alone is on target for making about US$1 million this year through that alone). Even if Google's take was the same as what they pay out, all-told that would be a decent whack of cash. But they're also thinking long-term. I don't think any of their "products" are anywhere close to the potential their brainiacs are envisioning.

So if you think the current state of affiars is scary, then you'd probably wet yourself if you spent a day as a fly on the walls at Google's HQ.

Bruno