Micros are really a completely different class from smalls and larges, because they offer "burst" performance. You shouldn't run anything in production on a micro, unless it's non-critical and not public-facing. Perhaps a 100% static web site, although even that I'm not sure about.
They can be appropriate for production workloads. You just need to understand the consequences of that burst performance. You also need to understand that you'll hit the invisible CPU usage limit without any notice.
You can actually run static web site from S3. Its really easy to setup, you can point your domain at a public S3 bucket. I put together this small website (http://www.de-encode.com/) to play around with it, seems to work well.
