- Is there any minhag to fill a cup of wine to the point where it overflows?
- Do some people overflow their cup because of Kos Pagum or does Kos Pagum apply to a cup which is not filled near enough to the top to be considered full?
- Is overflowing one's cup ba'al tashchis or davar megunah?
- Where is the halachic source that overflowing one's cup at havdalah is considered a berachah?
Four questions is a nice, traditional number :)
(As usual all translations are my own, and not quite literal unless otherwise noted.)