Quoth the Delicious Firefox addon TOS:
1. Licensed Uses and Restrictions.
b. YOU MAY NOT:
...
(iv) use the Delicious Software to operate nuclear facilities, life support, or other mission critical application where human life or property may be at stake. You understand that the Delicious Software is not designed for such purposes and that its failure in such cases could lead to death, personal injury, or severe property or environmental damage for which Delicious is not responsible.
It is quite unclear to me how one would use a bookmarking website addon for Firefox to operate much of anything, let alone anything like nuclear facilities or life support. Especially considering the restrictions in 1.b.i and 1.b.ii, which prevent any modifications or embedding of the software into hardware or firmware.
Considering the other provisions of this license—including their insistence on Santa Clara, California as the jurisdiction, regardless of any conflict of law provisions—I declined. I am now safe to operate nukes with my Firefox, I think. It's been a while since I read that EULA...