Hey there Pawel, the rate when I was there , in March '04 was US$ 270-285 and €340-380 to the oogie. Its best to change your $/€ into local currency as you will not then get ripped off for every transaction when they try and give you change at a bad rate.
The US$ is dead in West Africa, people dont want them and youll get a really bad rate everywhere, you are much better using the Euro.
The Mauritanian banks wont change TC's but there are plenty of Bureau de Change guys and shopkeepers always asking you if you want to change money. Forget your Credit cards too - cash is the best way in Mauritania.
Safe travels, Cheers, Grif.
[This message has been edited by Gipper (edited 24 May 2004).]