Joel at Far Outliers has an interesting post on how Koreans chose Japanese names during the Japanese colonial period. (Spotted on Language Hat.)
Regarding name frequency in Taiwan, I once did some checking of an old version of Chih-Hao Tsai’s invaluable list of Chinese names (in Taiwan) and ended up with the top ten names covering 50 percent of the population. Now that he’s got an improved name-list online, I should check again.
Also here in Taiwan, few aborigines have taken the trouble to change their official names, now that they finally have an alternative to the sinicized versions that had been forced upon them by Taiwan’s officialdom. It will be interesting to see how the situation changes, if at all, now that new national ID cards are finally being issued. For more on this, see Romanization to be allowed on some Taiwan ID cards, including the link in the note.