Twirus is filing a gap as Twitter spreads in usage globally. Currently, trending topics are only words in English, so other languages get left out. This is true even if they have a hotter topic than anything else.
The main page is a little busy and confusing at first, but filters exist across the top to see topics by language, region or timeline. Popular tags are listed down the right side with popular people down the left. Reading their about information, they take into account the popularity of the Twitter user in the rankings of the tags also since this is all coded by them.
A great tool for those joining in from other places in the world and want ways to follow hot topics from there. While there is only a few countries listed for now, I can see this service expanding.