My one piece of advice, and this is not confined to YC interviews but goes for any time you are selling (and make no mistake, you are selling), is to talk up the problem a little bit before you lead into your solution.<p>I expect PG and company are experts with regards to the needs of web startups and inexpert with regards to many fields of human endeavor. If you're going to be targeting one of those fields, mention the importance in ways which are easy for non-experts to understand. Our field is important: it employs X million, supports N companies on the Fortune 500, and did $ZZ billion in sales last year. Our problem keeps these people up at night -- they write journal articles about it, they spend hundreds of millions addressing it, it might even have killed a few thousand people they care about last year.<p>After you do that, people will be more inclined to view your solution in a positive light. Without the perspective of the problem, folks tend to latch onto things they understand about the solution: hmm, that button placement is off, this visualization lacks a bit of panache, I can't see myself ever really using this...<p>These are not the thoughts that typically precede writing big checks.