United Hosting offer both UK and US based, fully managed servers. They start from £200 / $300 per month. Recommended by Henry Dillon.
A hosting provider recommended by Happy Cogs (who designed the WordPress 2.5 admin panel). $20/month for shared hosting (1000 domains, 100Gb, 1Tb) , $50-$150/mth for virtual, $750/mth for a balls out dedicated server. Looks *very* good.
As at Mar 2008 you get 1.7Tb of disk and 17Tb of data for $9 a month (6 month contract). Useful for backup and media, etc. Probably too cheap to be reliable.
ServerBeach are a hosting company recommended by Tailrank's CEO Kevin Burton. Their servers start from $75/month.