First up, I hope you know that you can bump your Places API quota from 1,000 queries/day up to 100,000 queries/day just by verifying your identity? This doesn't cost anything. And if even 100,000 QPD are not enough, you can purchase a Google Places API for Business license.
But to actually answer your question, I'm not aware of any alternative that's both good and unlimited. The main competitors with worldwide coverage are:
- Foursquare Venues, which is limited to 5,000 queries/hour. Here's a lengthy point-by-point comparison of the two.
- Factual's Global Places, limited to 10,000 queries/day.
