The video clip for The Sweetest Thing was a present from Bono to his wife, after he forgot her birthday. During the short travel they take in the streets in this clip, some signs and banners saying "I am sorry" and "I love you" can be seen.
(Actually, I learnt this from MTV bytesize, so this might be inaccurate)


Also the name of a 1998 U2 single, featuring the following tracks:

Sweetest Thing (The Single Mix) 3:00

Produced by Steve Lillywhite with Daniel Lanols and Brian Eno
Recorded by Joe O'Herilhy and Pat McCarthy
Additional recording and mixing by Steve Harris
String arrangement by Daragh O'Toole
Strings: Una O'Kane, Nicola Cleary, Aengus O'Connor, Nicholas Milne
Special thanks to Ali Baba (??)

Stories For Boys (Live From Boston) 3:02

Recorded live in Boston, March 6th 1981
Recorded and broadcast by WBCN
Courtesy of Warner Bros. Records Inc.

Out Of Control (Live From Boston) 4:25

Recorded live in Boston, March 6th 1981
Recorded and broadcast by WBCN
Courtesy of Warner Bros. Records Inc.