What are some similar storylines from Marvel and DC, for instance:
* Millennium and Secret Invasion
* Kingdom Come and Civil War
* Post Civil War Captain America vs Post Final Crisis Batman
...I saw one site talk about 'House of M' and 'Flashpoint', but I really didn't follow those.
Any others you can think of? It doesn't have to be major crossovers. It can be similar storylines in individual books too.