I had hoped to create a list of Muslim organizations and individuals condemning the London bombing, because every time something like this happens, there are voices that say violence is an intrinsic part of the Islamic tradition, and claim that because no Muslims have denounced the violence, it must be true. However, Muslims are constantly denouncing violence, but we are speaking from soap boxes. The fringe of humanity (these terrorists are the fringe of humanity, not just Islam) will always be louder. While gathering my material, several other sites have compiled these condemnations, including non-English material. I am linking to those sites, and will try to keep this article as updated as I can. Please send as many as you can my way, or post in comments.
Juan Cole (includes the mythbuster that no Muslim has condemned OBL. Many a Muslim has denounced Osama, including major religious figures.)
Juan Cole 2 (On London specifically.)
Dervish Dua (1, 2)
Al-Muhajabah (continues, great resource list on condemning terrorism in general)
Global Voices (1, 2)
BritishAsian (personal note)