Sciencebase.gov
I registered sciencebase.com back in July 1999 entirely in good faith because it seemed like a great, memorable one word name for a website. The domain took over from various ad hoc web sites on disparate hosts I'd used since my first foray on the web in 1995 and became my go to site for all my science writing and the new home of my chemistry newsletter Elemental Discoveries. The image is a snapshot from the year 2000 entry for sciencebase.com from the wayback machine archive. You will note perhaps with interest how blog-like it was before blogs had even been invented.
As web 2.0, blogs and social media and online social networking emerged over the subsequent years I registered the term sciencebase with those various sites including the likes of wordpress, tumblr, twitter, facebook, myspace etc and have built up a substantial following based on my identity as sciencebase. It is therefore rather disheartening to discover that the United States' government in the form of the US Geological Survey has recently kidnapped my username in September of 2012 or thereabouts to create a geological database site called sciencebase.gov.
I don't suppose there's really anything I can do about it, they're a slightly bigger organisation than my two-person science-writing partnership. It's galling nevertheless.