What is the most widely spoken language in the world, outside of Chinese? Well, it depends on how and who you count as a native language speaker. On any list of top languages, Spanish is either number two behind Chinese or very close to the top. Most estimates put the number of Spanish speakers in the world at around 329 million. There are estimated to be over 20 million Spanish speakers in the U.S. alone. See study by the Summer Institute for Linguistics and other studies as quoted by Saint Ignatius High School and Infoplease. I don't think anyone would consider genealogy as a widely popular pastime or interest for Spanish speakers, but that might change as more and more Spanish language records become available on the Internet.
FamilySearch's Record Search continues to add more records, especially from Spanish speaking countries. Recent additions include records added to the 1930 Mexico Census, Mexico, Catholic Church Records, Mexico, Civil Registrations 1860 - 1950, and Mexico, Distrito Federal, Catholic Church Records 1886 to 1933.
Other new records in Spanish were added to the Argentina, Catholic Church Records, Costa Rica Church Records 1595 - 1992 and Puerto Rico Civil Registration 1836 - 2001. Record Search's collections are not limited to Latin America, new records were also added to Spain, Catholic Church Records 1500 to 1930 and Spain, Municipal Records.
Although records have been added to the above collections, some of the collections are still incomplete. For example, the Mexico Catholic Church Records now cover 14 of 31 States not counting the Federal District which has its own collection of records. Another example, the 1930 Mexico Census is now 62% complete. Additions to the Spanish Catholic Church Records bring the total to 7 out of 52 provinces. If you are interested in researching in any of these areas, it is a good idea to check the progress of the collections from time to time. There is no where else on the Internet where such are large number of original source records in Spanish can be easily found.