There's no good reason to start a project with other databases. If you're worried about the scalability of something like MySQL when you haven't even got your first 1000 users, your priorities are messed up. Finish your product and get your users first. And I hope to god if you DO get your users and I ever have to maintain it, it's not running on some bullshit like Tokyo.
Re: Poll: What database does your company/you use?
#31A word of opinionated advice to anyone deciding on a database to use for their new project: Just go with something popular (MySQL, Postgres, Mongo, etc.), or go with an Amazon hosted cloud database if you really don't want to set anything up (RDS, SimpleDB, DynamoDB).