I've had to ask for plenty of letters in the past and I never thought to give anything more than a sincere letter of thanks and followups on what happened in my future. It may be that I primarily have asked for letters from faculty, who for the most part consider it part of their job. It may be different if you are away from school, but when I think of my relationships to professors I would guess that getting a bottle of wine from a poor college student might be a bit mutually embarassing. They do get upset if you don't tell them where you got in / how things worked out.
I have tried taking them out for coffee afterward, but they usually insisted on paying.
With this, I completely agree. As long as you fall into the undergrad - 5 years out range. The professors I've spoken with about this (or who have spoken out about it) have all said some variant on the above. Updates = expected. Hallmarks = appreciated. Anything else = inappropriate . (YMMV)
I should add, that I'm speaking in the context of LOR thank yous -- there seems to be different rules for student-professor gifts in other circumstances (e.g. thesis advisor, mentor, etc.)
Later in life, in other 'thank you' contexts, it's a different story. (And personally, even in terms of an academic context, I'm planning on thanking some of my professors -- recommenders or otherwise -- in a big way with significant departmental and research-grant donations over the years. But not now, and not because of LORs.)
This is, obviously, my own position. Different strokes for different folks as the saying goes...