Muse Games is an independent games development studio based in New York City.
We’ve been using this for a long time. It covers what we need to do.
Mandrill is the underlying email distribution service for MailChimp. It's much cheaper, and we've built some of the analytics ourselves.
Google Drive is easy to use, and covers our general file-sharing needs.
Dropbox is very easy to use.
Insperity covers all HR admin, insurance, legal and payroll for us, so it's very all-encompassing. It has good insurance rates (slightly better than ADP), and great legal clout. It's helped us work through bogus government claims.
Trello is easy to use, great for sharing, and covers our production pipeline well.