Is it constitutional for a former US president who has served the full 2 terms already to be elected vice president? He wouldn't be going for a 3rd term so it could technically be considered comstitutional, but if the president died, then he would be president for his 3rd term, which I believe is not constitutional. Is this possible? I've thought of a possible solution, but I don't think its right... Does anyone know?

No. Just for the reason you listed ... he could be president if the president is removed from office. It will never happen.

the 12th Amendment states that if you are ineligible for president, you're ineligible for Vice President so if you've already serve two terms, you're ineligible. But I don't know if that applies to term limits.

 @madskillz

Well, thats just it. The chances of that happening are not too terribly high, so the odds that he wouldn't serve a third term seems likely. I was leaning towards no as well, but I'm just not completely sure...

It also excludes Arnold ...

No person except a natural born Citizen, or a Citizen of the United States, at the time of the Adoption of this Constitution, shall be eligible to the Office of President; neither shall any Person be eligible to that Office who shall not have attained to the Age of thirty-five Years, and been fourteen Years a Resident within the United States.

 "The Twelfth Amendment explicitly precluded from being Vice President those ineligible to be President: people under thirty-five years of age, those who have not inhabited the United States for at least fourteen years, and those who are not natural-born citizens. It is unclear if the Twenty-second Amendment's term-limiting provisions prevent two-term Presidents from becoming Vice Presidents (see that article for a fuller discussion)."

http://en.wikipedia.org/wiki/Twelfth_Amendment_to_the_United_States_Constitution

It doesn't say anything about terms. maybe that is implied? Or maybe I should just ask the Supreme Court...

Here's the info ...

Amendment 12 - Choosing the President, Vice-President. Ratified 6/15/1804. Note History The Electoral College

The Electors shall meet in their respective states, and vote by ballot for President and Vice-President, one of whom, at least, shall not be an inhabitant of the same state with themselves; they shall name in their ballots the person voted for as President, and in distinct ballots the person voted for as Vice-President, and they shall make distinct lists of all persons voted for as President, and of all persons voted for as Vice-President and of the number of votes for each, which lists they shall sign and certify, and transmit sealed to the seat of the government of the United States, directed to the President of the Senate;

The President of the Senate shall, in the presence of the Senate and House of Representatives, open all the certificates and the votes shall then be counted;

The person having the greatest Number of votes for President, shall be the President, if such number be a majority of the whole number of Electors appointed; and if no person have such majority, then from the persons having the highest numbers not exceeding three on the list of those voted for as President, the House of Representatives shall choose immediately, by ballot, the President. But in choosing the President, the votes shall be taken by states, the representation from each state having one vote; a quorum for this purpose shall consist of a member or members from two-thirds of the states, and a majority of all the states shall be necessary to a choice. And if the House of Representatives shall not choose a President whenever the right of choice shall devolve upon them, before the fourth day of March next following, then the Vice-President shall act as President, as in the case of the death or other constitutional disability of the President.

The person having the greatest number of votes as Vice-President, shall be the Vice-President, if such number be a majority of the whole number of Electors appointed, and if no person have a majority, then from the two highest numbers on the list, the Senate shall choose the Vice-President; a quorum for the purpose shall consist of two-thirds of the whole number of Senators, and a majority of the whole number shall be necessary to a choice. But no person constitutionally ineligible to the office of President shall be eligible to that of Vice-President of the United States.

I'm glad you can give a civic's lesson. 

^Yes, ask the Supreme Court, because if such a thing should happen, the Supreme Court will probably be the one to decide on the matter, and their word is law.

"Section 1. No person shall be elected to the office of the President more than twice, and no person who has held the office of President, or acted as President, for more than two years of a term to which some other person was elected President shall be elected to the office of the President more than once. But this article shall not apply to any person holding the office of President when this article was proposed by the Congress, and shall not prevent any person who may be holding the office of President, or acting as President, during the term within which this article becomes operative from holding the office of President or acting as President during the remainder of such term.

Section 2. This article shall be inoperative unless it shall have been ratified as an amendment to the Constitution by the legislatures of three-fourths of the several States within seven years from the date of its submission to the States by the Congress."

http://en.wikipedia.org/wiki/22nd_amendment

I was also wondering if the 22nd amendment could have any effect on this.

But they won't select an ex-president to be vice president OR Speaker of the House. Like Nancy Pelosi - literally, she's two heartbeats from the presidency.