Caduet (new) = Lipitor (off-patent in 2011) + Norvasc (patent protection ended 2007 after a suit). Zocor (2006) + Zetia = Vytorin.

There are hundreds of examples -- this is a totally standard patent expiration strategy in medicine. This whole area is called "ever-greening".

The weirdest one is getting an existing drug approved for a new use. This can be used to extend patent protection.