The "Escape theme" from Metroid: Fusion. Particularly around 0:14 to the part where it says "Two minutes to detonation".
This one would fit in nicely with BL.Also, can we hear a preview of the second one?
The sound you hear in Half-life when you're near something radioactive, but looped into an OGG.
It's called a Geiger counter.http://en.wikipedia.org/wiki/Geiger_counter