[jmw]

I'd definitely recommend http://rimuhosting.com

I know of at least 1 YComb startup that has used it in the past - and we're using it now. I've personally been hosting with them for 2 or 3 years now and it's hands down the best virtual hosting I've used (compared with 4 others I've tried).

Other friends are using Amazon EC2+S3 for scaling needs (on the fly load-balancing). Haven't used it myself, but I only hear great things.

[mgiles]

I'd second that vote for Rimu. I used them when I started Furl and I continue to use them for my new projects. They are truly fantastic when it comes to support.