(1) Hugely improbable specialist etailers like iwantadoor.com advertising (indeed sponsoring) prime-time TV shows. When I saw them appear in the sponsorship slot tonight I immediately knew I was looking at the next Pets.com. That's not a happy connection for any company and it's not a happy moment for our market.
(2) Massive valuations placed on stocks that have never returned a profit. Demand Media (even with all its weird accounting) still wasn't making a profit when it got listed at $2bn. HuffPo just got bought as it went into marginal profitability. People are spending billions to own businesses that have yet to return a penny. That's not healthy, rational investing. That's dumb money hitching itself to a rising bandwagon (yes, I just said "rising bandwagon") and hoping to offload the shares before it falls.