There are two of us and we are both technical (and we have just hired our first non-founding team member, also a developer). My partner is a rare hybrid of brilliant developer and competent designer, something I am very grateful for.

Both of us have a background in high-performance computing and that has helped keep hardware costs down to a minimum - we served up to 2.7 million users from one single server and it wasn't until we switched to MongoDB that we had to buy more servers.