That was the island country of Nauru which sent one athlete to the 2008 Games. That was weightlifter Itte Detenamo who finished 10th in the super heavyweight class.
USA
india
Maybe Sri Lanka
That was 204 countries at the 2008 Summer Olympics in Beijing.
The Olympics caused all- sorts of problems for Beijing many due to the amount of people there as there were problems like sewage in the streets as the sewers over flowed and loads of rubbish was dropped in the streets and also the shear weight of traffic caused many pollution warnings! I.J.P :)
The most amount of gold medals ever won at a single Olympic swimming competition was 8, and it was done by Michael Phelps of the US at the Beijing 2008 summer Olympics.
Nauru
There are alot of athletes that went to the Beijing 2008 Olympics. 433 athletes went to the 2008 Olympics, which is the second most amount of Australian athletes that have gone to the Olympics Athens was first with 482 Australian athletes that went.
Sierra Leon has 2.
China
The Olympics has more country's but the gymnaestrada is the biggest participant event in the world with double the amount of participants.
The largest amount ever to attend the opening ceremonies of an Olympic games, over 100 heads of state and world leaders arrived in Beijing to watch at the Olympic stadium. A full list can be found at Wikipedia (link below)