I work very close to where the explosion was. --I've never felt a building shake like that! Needless to say, we didn't know exactly what had happened at the time, but we knew it was bad enough that we should take heed of the fire alarm going off and leave the building.
Honestly, my plan is not to let this change my life or routine. If I don't do that, then I've let someone else take control of my life.
Of course, the gym I go to is going to be closed this weekend (they're even closer to the blast site than my office), but they've already posted that they'll be open again on Monday, so I have hope that Oslo - and Norway as a whole - won't let this change their society.
I meant directly in the aftermath. Secondary attacks on groups of onlookers to the first attack are calamitous. Think a car bomb or rifle attack on first responders/EMTs. And of course now we know he had designs on additional attacks.
A few pictures I took of the area, about 1-2 blocks away from the explosion: http://twitpic.com/photos/tallanvor