Light up some candles, since you've just missed Storm's birthday. To those of you who don't know what Storm is, well, it is the virus with the biggest botnet (essentially, a group of zombie computers controlled remotely) since a lot earlier in the decade. It is assumed that Storm's botnet has at least 1,000,000 PCs.
Storm was unleashed upon the world in November 2006, by the name of Nuwar, due to the spam mail by which it came, which dealt with an unavoidable nuclear war between the USA and Russia. This spam mail contained an attachment which would turn computers into bots. The botnet would engage in mass-mailing penny-stock-fraud spam.
Later the spam was changed into New Years' greeting cards and only in January 2007 it became known as Storm, a name coined by F-secure because of the messages about a deadly storm that had killed hundreds in Europe. The spam changed a lot over the years ranging from online love letters to missile attacks to naked teens and so on.
Mass-mailing schemes were not the only thing carrying the Storm infection, there would also be invisible infections on a variety of websites. Even though none of these tactics are particularly new or original, the thing that made Storm what it is now is the constant change in technique, which helped it stay a step ahead of security vendors.
There have been speculations that Storm would sell off its botnet, but there have been no further news regarding this fact.
Whatever might be the case, Storm will most probably keep on growing.