The boycott scares during the cold war era rubbed The Games on the wrong side but eventually the Oly movement survived and emerged more stronger with more and more countries taking part in the post cold war period. From Seoul Oly in 1988 to the previous games in Athens no boycotts were reported. However when Beijing's candidature got the nod in 2001 to host 2008 games many believed that there would be more boycotts in support of Tibet's cause but so far no boycott call from pro-Tibetian nations including United States have registered. OneIndia enlightens you on Oly boycotts...
1956 Melbourne Oly: The Soviet invasion of Hungary provoked protests from numerous western countries and some of them, such as Spain, Switzerland and the Netherlands, withdrew from the Games. Egypt, Lebanon and Iraq refused to participate in protest of the Franco-British Suez intervention. And the People's Republic of China refused to participate because of the presence of the Republic of China (Taiwan). This conflict would take 28 years to be resolved.
Montreal Oly 1976: Tanzania-led African nationa-as many as 22- boycotted the Games in protest against New Zealand's participation in Montreal Games as Kiwis Rugby team travelled to the aparthaid South Africa. The IOC tried to convince African nations that Rugby was not a Oly sport and it isn't fair to prevent NZ from participating. But the African nations were in no mood to relent. However despite African nations boycott the Games were successful, thanks largely to galore of individual brilliances including that of Nadia Comeneci, Aleksander Dityatin, spitz et al. In the same event People's Republic of China (Mainland China) refused to participate as Taiwan participated under Republic of China.
Moscow Oly 1980: The Olympics were disrupted by another, even larger boycott, this one led by US president Jimmy Carter, part of a package of actions to protest the December 1979 Soviet invasion of Afghanistan. Carter engaged in extensive arm-twisting to gain support from other nations. Some governments, like those of Great Britain and Australia, supported the boycott but allowed the athletes to decide for themselves whether to go to Moscow. No such freedom of choice was allowed US athletes, as Carter threatened to revoke the passport of any athlete who tried to travel to the USSR. In the end, 65 nations turned down their invitations to the Olympics; probably 45 to 50 did so because of the US-led boycott. Eighty nations did participate - the lowest number since 1956.
LA Oly 1984: With the Olympics being held in the United States only four years after the US- led boycott of the Moscow Games, it was not surprising that the Soviet Union organised a revenge boycott in 1984. This time only 14 nations stayed away - but those nations accounted for 58% of the gold medals at the 1976 Olympics.