I have been to the following derbies so far:
Inter-AC Milan (January 2010)
Werder Bremen-Hamburg (September 2010)
Rangers-Celtic (February 2011 and March 2011)
Roma-Lazio (March 2011)
Before this i was a season ticket holder at Chelsea up until the end of last season (got too expensive, atmosphere completely gone although it did go a long time ago if im honest,lost interest in the premier league and took a more solid interest in international football, bundesliga and Serie A, many of the players don't have the passion and i feel like a lone wolf questioning why John Terry should ask for a pay rise on a yearly basis) Went to the world cup too and been to a few 'smaller bundesliga matches' such as a few Schalke and Bayern Munich matches. Also went to a lot of Millwall games when i was young with my schoolmates but that's a different story. Always had a soft spot for Everton but only been as a Chelsea fan, would love to go a few Everton games next year and see what the vibe is like.