sunriseIf you’re still stuck in the queue to get access to iPhone email app Mailbox (currently more than 800k people are), comfort yourself with another server-based productivity app: Sunrise Calendar. Which has no waiting list.

The app launched yesterday, and aims to replace the default iPhone Calendar app rather than its Mail app. Sunrise gets users to sign in to their Google Calendar account, and optionally into Facebook and LinkedIn too.

It then pulls down data from these services for a slick, innovative calendar app.

“Calendar apps today are mostly broken as they don’t show you useful information, even though you spend a lot of time adding items every day,” developer Pierre Valade tells TechCrunch. “We looked at this underestimated issue because nobody wanted to redefine the underlying principles of existing calendar apps.”

One impressive thing: Sunrise is a bootstrapped startup, with no external funding as yet. This may also be a concern though: if 1m+ people suddenly start using the app – and with no Mailbox-style waiting list or fee to download the app, that’s possible – will Sunrise’s servers scale quickly enough to cope?

The app’s free nature should also spark questions about the likely business model. It’s a really impressive, useful app, but experience is rapidly teaching smartphone users to wonder how their data will be monetised by such free services.