Mexico has an interesting law that requires the Congress to approve any foreign trip for the President. This law kept past President Vicente Fox home twice late last year before leaving office. Mexico's brand-new President, Felipe Calderón, is not popular with Congress and the legislature has threatened to also keep him within the territory if they disagree with him. Some suggest the law should be change as it is a bit "provincial" and makes Mexico look bad on the world stage. More from the Washington Post.

Comments
I don´t agree with you in that Calderon is not popular with Congress. Maybe on December 1st was a very rude day, but since then the relationship has changed, for example the Budget for 2007 was aproved almost for unanimity.
Calderon has leaving out the protagonic style of Vicente Fox surprising to many people, including me, making the relationship with the Congress more terse in a month and a half, so the important reforms (electric, fiscal, social security) can be discussed and aproved.
I think the President should be able to leave the country without any one permission.