The social networking site Friendster, while long-dead in its birthplace of North America and subject to Anyone Remember Pogs?-style jokes by The Onion, remained theFriending Network in large parts of East and Southeast Asia during the mid-late '00s (to the point where it moved its headquarters to Kuala Lumpur), eventually morphing into an equally popular social gaming site in 2011. At last count, the top five countries using Friendster were the Philippines, Indonesia, Malaysia, South Korea, and the US.
The Orkut social network, created by Google, out of all the possible countries, is very popular in India, Estonia and especially Brazil. In fact, Orkut became so popular among Brazilians within a year of its launch that many of its American users fled. A few years later, Orkut's headquarters were moved to Brazil. It's one of the most popular websites on the internet, but largely unknown in its country of origin, where its parent company is a household name.
Another social networking site, Hi5, is based on California yet around 80% of its users live outside the US. For a while it was the most popular social network in Latin America, Portugal and Thailand (though the rise of Facebook has severely reduced its popularity in some of those countries). Currently, they're trying to follow Friendster and turn the site into a "social gaming" platform.
Fotolog, despite being headquartered in New York City, is extraordinarily popular in Spain and South America, to the point where the Argentinian equivalent of emo/scene fashion was known as the "Flogger". Eventually, though, as Facebook started to gain more acceptance in Argentina, and a few violent episodes covered by the media involving Floggers, starting in March 2009 (end of summer vacations) Flogger fashion started to lay down quietly.
The lesser meme "Leekspin" has become a major Runet (Russian Internet) meme under the name "Yak tsup tsop" in 2006. Subsequently, the song itself ("Ievan Polkka") and its performers (the Finnish band "Loituma") became extremely popular, too, resulting in fansites, cover-versions, ringtones, etc. Orihime Inoue, who was featured in the original flash animation, became something like a symbol of the whole yak-tsup-tsop craze; and (due to most Russians not knowing who Orihime in fact was) was considered a made-up character and nicknamed "Ieva" (after the song's main heroine). There even were some Rule34 pics of "Ieva" (not Orihime!). Orihime is sometimes referred to as the "Loituma Girl" as well.
Similarly, both leekspin and caramelldansen have gone on to be major memes in Japan, with the former leading to Miku Hatsune often being drawn holding a leek, and the latter leading to a wide variety of custom versions of the original caramelldansen gif, which triggered a second, larger wave of popularity in America. In fact, people who didn't know had to be told that the song was Swedish, NOT Japanese.
Caramelldansen videos are now an Ascended Meme due to the original band making an official music video to the Speedycake remix in which they are all depicted as animesque characters doing the very dance that originated from the meme. Warning, Uncanny Valley material in the video.
The instant messaging protocol ICQ, though popular in the late 90s, fell out of favor along with the company that had purchased it, America Online. However, this is not the case Germany, Russia, and the rest of Eastern Europe where it equals instant messaging itself. Indeed, since April 2010, the rights to ICQ have been held by Russian investment group Digital Sky Technologies.
British YouTube user xBextahx somehow became very popular in Japan, where she is known as Beckii Cruel. Her popularity in the UK and US has since gone up due to her collaboration with Area 11 on "Shi no Barado", as well as subsequent appearances with In The Little Wood.
There's also Magibon, a Pennsylvanian twenty-something with a propensity for staring at the camera who's practically become a celebrity in Japan.
When an American father named Allen Rout posted a picture of his newborn baby on his website, he'd never realize years later that it'd blow up into a Memetic Mutation in Japan.
For unclear reasons, LiveJournal is the most popular host for Russian-language bloggers, to the point where the Russian term for blogging is derived from the Russian name of LiveJournal. A Russian company now owns the site, a number of high-profile Russian politicians maintain LJs, Russian authors used LJ to publish excerpts or teasers for their new books, and it's even been theorized that the DDoS attacks on the site in April 2011 were caused by the Russian government in order to silence a critical blogger. LiveJournal is Serious Business in Russia.
eBay knockoff Yahoo! Auctions quickly faded away everywhere except Japan, where it is by far the most popular site of its kind.
Omegle is infamous for its amount of Indian and Turkish users.
Twitter is very big in Japan, and is popular enough that when Twitter shut down its more popular version 1.0 API in favor of the newer v1.1 API, "API" became a trending topic in Japan, suggesting that the change was rather controversial, while most Western users of Twitter were apathetic at best. It also helps that in Japanese, the same information can be conveyed in less characters than in most Western languages; a 140-character tweet in English may only have 2-3 complete sentences, while a short essay can be written in a 140-character Japanese-language tweet.
Bebo was founded in America, but at its height in the mid-late '00s, it was the social networking site... in the UK and Ireland, where it overtook Myspace in popularity by 2007. Much as Myspace was synonymous with the Emo Teen, Bebo grew associated with the uniquely British "chav" stereotype.