Looking into this charge of the US sending detainees to foreign countries for torture, I will start with two articles on Wikipedia that summarize things:

1) The case of Maher Arar (http://en.wikipedia.org/wiki/Maher_Arar)
2) Extraordinary rendition (http://en.wikipedia.org/wiki/Extraordinary_rendition)

The astute reader will note that nowhere in either article is the word "alleged" used. The concept of "extraordinary rendition" seems to be accepted by the author(s) as official US policy.

I would argue that it is not.

Here is an interesting timeline on the Arar case: http://www.cbc.ca/news/background/arar/. There are some important facts to note:
1) Arar holds dual Canadian/Syrian citizenship.
2) Canada was asked to incarcerate Arar and charge him. When they refused, he was sent on to Syria - of which he is a citizen.
3) Arar was under investigation before he was deported.
4) Arar was detained a little over a year after 9/11. This probably had quite a bit to do with how he was treated.

I am not privy to the court proceedings, so it is impossible to say if Arar is guilty of what he was accused of or not. The question is, was he sent to Syria with the specific understanding (by the US) that he was to be tortured? I have strong doubts. Syria is not known for its treatment of prisoners, foreign or domestic, and I would charge that what Arar experienced is not unusual for any other Syrian political prisoner (which, in effect, he was).

In regards to the concept of "extraordinary rendition", please note that most of the other cases involve persons being returned to countries that they either originally came from, or hold dual citizenship to. Are they being returned to these countries specifically for the purpose of torture? I don't believe it. Study after study has proven that torture is pointless, and after decades of dealing with Cold War spies, surely the CIA has much more effective means of getting information from people.

Regarding the so-called "torture flights" that the CIA allegedly conducted, I will submit http://news.bbc.co.uk/1/hi/world/europe/4439036.stm. The key paragraph is this:

Spain's Defence Minister Jose Bono reacted cautiously to the Majorca allegations on Tuesday, saying "we do not have any evidence, we do not have any proof".

Read the articles, do more research, and draw your own conclusions, folks.