Would this do any damage to my car? It is a 3.8 v6 Pontiac Grand Prix.
Disclaimer: I've never tried this myself.
Is it close to being time to change the oil filter? Depending on its position, you should be able to spin it off without losing much more than the oil contained within (which should be ~0.5-0.75 litre). Replace it with a new (empty) one and run the engine for a minute or two then recheck the oil level.
Depending on whether your oil filler tube goes into the block or into an OHV cover, you might be able to syphon off a litre or so through it.