I've had to institute a new rule as of late with my collection growing like it is: I'm not allowed to have a glass from that brewery unless:
A) I've been to the brewery, or
B) I've had beer from them; preferably I have beer in my refrigerator/cellar.
There are exceptions to this (there are always exceptions), but in general that's the rule and i call it the "proper beer rule". It's led to a lot of trades where someone sends a beer along with the glass to ease past this.
The half acre glasses below are a good example of this rule and trade scenario.
What: Half Acre "crab" glass and Half Acre Snifter
How: IG and BA trades