I have used them as flasks to hold 7.01pH and 4pH solutions individually, to calibrate my pH meter, and then cap for future use. They are wide enough to accept both the electrode and temp probe, while using less fluid than a flask. Might not do so anymore, since I have a new benchtop model coming from Valley Vintner. I use the meter for wine, and ColorpHast strips for beer.
I definitely will use some for salad dressing to take to work.