To continue for at least a bit more on the topic of Department Seminars..
Some places provide refreshments before a department seminar, some places provide refreshments after, some provide refreshments during a seminar, and some provide no refreshments whatsoever.
Are refreshments important: for seminar attendance? for impressing the visiting speaker? for enhancing general socializing in the department? for sustaining a building's non-captive rodent population?
It depends on the refreshments.
Most indications are that refreshments help attract attendees, particularly of the student species and perhaps also others. I think it is also a nice social thing to do.
Does it matter when the refreshments are served or what they are?
For some people yes, for others no.
My personal preference is for refreshments after a talk, as this encourages discussion and socializing of department members with each other and with the speaker. If the socializing is after the talk (and the seminar is scheduled for a time that allows most people to stay for 15-30 minutes afterward), this is a good opportunity to chat with the speaker about what he/she just presented.
If talks are scheduled for rather late in the afternoon and many people have to leave immediately after the seminar, then it is best to have a brief social interval before the talk, ideally accompanied by some refreshments that don't have too dramatic an effect on the biochemistry of the audience.
As a speaker, I try not to take advantage of pre-talk refreshments if these items consist of cookies, doughnuts, and coffee. Even if I found the prospect of getting hyped up on sugar and caffeine just before a talk appealing, I think it would be a very bad idea for me to do so.
Apres-seminar refreshments encourage people to linger a bit and chat. I like this informal chatting time, as a speaker and an audience member. It's a nice way to unwind and talk to a variety of academic creatures, whether or not they are munching on tortilla chips at the time.
8 years ago