International - What countries don't allow visitors with a drug conviction?

[~lostgurl~]

What countries don't allow visitors with a drug conviction?

From what I have heard, mostly through the grapevine, is that America and Singapore are just 2 of many countries who do not allow visitors into their country who have drug convictions. I'd like to know what other countries are on this list?

Also does this apply to all convictions or specifically to drug convictions?

A special visa can be obtained in some cases but does anyone know how difficult it is to actually obtain one of these?

Anyone convicted of or punished for a crime involving moral turpitude (regardless of how long ago or if the conviction was not recorded) is ineligible for the Visa Waiver Program and must apply for a visa. If there is any doubt regarding the nature of the offense, it is advisable to apply for a visa.
The applicant submits details as to the court date, the type of offense, and the outcome, usually with a police certificate or court documents. If the police certificate says "no recordable convictions" but the person has committed a crime he or she must seek out court documents. He or she must also include the port of entry and exit to/from the US and the expected dates of travel. This information is in addition to the usual requirements for the type of visa being applied for.

http://newzealand.usembassy.gov/niv_faq.html