The two screw-like plastic connectors that secure the front grill on my SAAB 9-5 don't hold like they once did. I used silicone adhesive on the slots above the connectors to stick the grill in place and end the rattling. The silicone can then be removed with just my fingers when I need to pull the grill.
Photo of the secured grill
Silicone is also great for holding the little plastic squares under the car that anchor the screws for the plastic splash guard. It seems one of those pops out every other time I go to remove the guard.
It is sticky enough to rescue small items in tight places. Just put a little on the end of a screwdriver or dowel rod and fish out that lost washer.
I use it just about any place I need to securely hold something that I might want to remove some day.