Peru has a couple old ones:
Cruiser Almirante Grau
Launched: December 19, 1941
Commissioned: November 18, 1953
Still in service
http://en.wikipedia.org/wiki/BAP_Almirante_Grau_(CLM-81)
Hospital Ship Puno (is apparently powered by a Llama Dung Engine)
Launched: 1872
Commissioned: May 18, 1872...