My suggestion: Abide by the NDA. Think this through. You're a small, early stage company. If a leak comes out, do you really think the buyer is going to believe that it came from anywhere but you? How does that make you look to them? What's more likely to happen: they're going to offer a much higher price as a result of a bidding war, or they're simply going to walk away? If you show yourself to be a person or business that doesn't negotiate in good faith, no one is going to be willing to work with you. The last thing you want is a large angry corporation with better, more expensive lawyers than you can afford coming after you for a breach of contract.

Long story short: Abide by the agreements you sign.

Seconded. The concept of "leaking" information outside of your NDA pretty much defines that there's no "proper" way to do it.

OK then. I tend to agree. Let me rephrase: what can we do (within legal boundaries) to initiate a bidding war :)