The DOW Industrials are at a P/E of 16.2, historical averages since the 1880's is 16.6, there's no huge bubble or crash coming unless it's an international contagion from Greece or China that halts world economic progress.
The DOW is not a good benchmark for investigating if there is a bubble or not. It is comprised of just 30 companies, mostly huge conglomerates and industry titans. There are also little to no "new" businesses on the list. The tech companies on the list are very mature, and include Apple, Intel, IBM, and Microsoft. As far as companies that are trading at a "fair" price, I would say the 30 companies in the DJIA are priced very fairly because of all the eyes on them.
If there is a bubble, it is almost surely not reflected in the DJIA. Let's say, for argument, that there is a bubble (you don't have to agree, just for the sake of argument). Where would it manifest? Technology companies founded in the last 10 years? Tech companies founded in the last 3 years? Those are the likely candidates in my opinion, but they are not represented in the DOW 30 AT ALL.
Maybe you think the next bubble will again be in banking? In that case, only Goldman Sacks, Visa, and Chase represent the banking industry on the DOW 30. I have the opinion that if there is a serious disaster brewing, those 3 companies can keep it from affecting their balance sheet until the last possible moment. They were fairly successful in doing so in 2009 so I have no doubt they could and would do it again.
My point is that if you are looking for a bubble, looking at the DJIA is a complete waste of time. P/E ratios may not be the best indicator either- in 2008/2009 the P/E ratios didn't make alarming moves until *after* everybody knew there was a big problem. You're relying on every other investor to tell you that things are OK (by assigning a fair Price), but every other investor may well be stupid. The best indication I think is what companies are paying when they buy other companies. Are they paying reasonable prices that will allow them to earn a profit on their investment? If they are buying a company to protect market share, is their investment at least as much as the potential losses if they hadn't bought the company? If the answer to either question is no, that's a big problem. It means they have so much money that they don't know how to manage it, or it means that they are basing their decisions on emotion, and not numbers. Either of those is a recipe for disaster.