In many civilized and relatively non-corrupt jurisdictions, judges nonetheless tend to get... shall we say, petulant when they feel they've been wronged.

(and I say "relatively" because of things like libel tourism and superinjunctions, both of which enable corruption to various degrees)

How often does something like the recent extradition of the operator of a site the UK deemed not worth prosecuting happen?

Presume you're referencing Richard O'Dwyer (tvshack.net), who a magistrate recently found was suitable for extradition to the US. This is quite rare, there have been 99 extraditions since 2006, of which 35 were british nationals, so although extradition is reasonably rare it is not entirely uncommon. Also, you say the UK found the alleged crime was "not worth prosecuting", which is loosely technically true, it doesn't really give the full picture: His actions were found to be legal under UK law and so hence there was no case for prosecution. His operations are, however, suspected of being illegal under US law and so hence the case for extradition was submitted.

To bring this back to the parent discussion: Few would argue that Mr O'Dwyer has been unfairly treated with respect to the current law. Some do, however, argue that it is the extradition statute itself that is unfair, with Mr O'Dwyers case being an example. As a matter of interest, Theresa May has recently announced some changes to the extradition process following the results of the Baker Review. (http://www.homeoffice.gov.uk/media-centre/news/gary-mckinnon...)

There are other examples, but this is a function of our executive's decision to bend over to US demands and rewrite UK law, rather than corruption of the legal system itself.