First of all, a tourist/visitor may enter the country of Colombia and stay usually up to three months simply on your US Passport.  No visa required.  This includes multiple in and outs, say a visit to Ecuador, or a quicky back to the states.  The tourist mat renew his stay by going back to the states and then returning.

But then there are the longterm visas perhaps leading to Residency incl all the benefits of health care paid by the government mostly,

These visas must be obtained at a Consulate of Colombia in the US like in San Francisco or LA or  NYC.  Check the wb for Consulados near you.

MORE ON BOTH RENTISTA AND PENSIONADO VISAS... uh oh, if you are here as a tourist, do you have to do this back in the states???  I think so.

There are student Visas established by universities here and corporate visas for employees of US companies.

But here are two more available to most anyone.

Foreigner with a Monthly Financial Income (Rentista)

This is another temporary (non-resident visa) and it would be best suited for people with a stable monthly income that comes from qualified sources.

Proof of your monthly income can be:

A certificate issued by a public entity, bank, financial company, social security institution, insurance company or any other private enterprise recognized by the respective government, that shows the applicant receives a monthly income of 10 minimum Colombian monthly salaries (around USD 3,300 in 2012).  Uh oh, you may need the original nota photocopy or a FAX and it must be notarized and apostilled.  An apostille is a guarantee by your state that the Notary is licenced.  In CA this can be gotten at the Sec of State's Office in Sacramento or LA.  (Not in SF!!!)
A contract with your employer showing you are earning a salary that is not less than 10 Colombian minimum monthly salaries.
Holders of a Rentista visa can invest and work without restrictions, provided that they don't work in regulated professions (i.e. law, medicine, architecture, etc).

The visa is valid for 1 year and it is renewable in BOGOTA at Colombian Sec of State office, and maybe (!!) via internet to Bogota.. The applicant can extend his/her investment visa to the following beneficiaries: Spouse/permanent partner, children and/or parents, provided that the said beneficiaries depend economically on the applicant.

After holding this type of visa for a continuous 5 years, one is also eligible for a "qualified resident visa" (see Temporary Visa Due to Investment section). Of course, there is a little more time involved in the whole process, but the fact is that it is possible (at least on the paper) to obtain Colombian citizenship just by living in the country as a retiree.

Pensioner (Pensionado)- NO AGE QUALIFICATION!!! This is what I have.

Here is yet another temporary type of visa that is renewable every year. Interestingly, there are no age requirements for this type of visa. All you have to prove is that you are receiving a pension from a public or private entity in your country (SSI< STRS< PERS ETC), and that your monthly pension is no less than 3 legal monthly minimum wages (around USD 990).

Just like in the other types of visas, beneficiaries are included here as well, so long as they depend on the applicant financially. One can again be eligible here for a "qualified resident visa" after holding this visa for 5 continuous years.