+ Working on a problem that the big company doesn't see that expands the market. Then the acquisition becomes a matter of buying into the market.
+ Working on a corner case in the big company's market and executing better. In this case the acquisition is amounts to buying a feature.
+ Solving a problem for users in a way that obsoletes the big company's fundamental business model. The acquisition amounts to stifling innovation.
+ Just being so awesome that acquiring your company is the only way to hire your team.
Despite arguments to the contrary, thinking about possible exits is a virtue not an ethical failing. Psychic income is great, but it doesn't always pay the bills. On the other hand, the likelihood of a random outsider having a highly useful model of Google's workings to the degree that being bought by Google is a viable exit strategy on day zero are pretty low [though an insider and industry veteran might be another matter].
Good luck.