Wikipedia is the place for all factual, verifiable, minimally notable information. When stuff gets rejected from WP, it's almost always because it fails one of those three simple tests.
For instance: someone downthread complained that WP was missing coverage of local bands and an interesting BBC documentary. The BBC documentary should be in Wikipedia, and if it isn't, it's probably because whoever wrote the stub article for it wrote it poorly; someone else should re-add it. But the local bands most likely fail both notability and verifiability: if nobody has written about them, (a) chances are they aren't notable, and (b) whatever is notable about them can't be tied to a specific reliable source, which would make a Wikipedia article about the band original research.
A really common place you run into trouble with Wikipedia is when your proposed article breaks new facts about its subject. That's not supposed to happen. Wikipedia is a tertiary source; if it makes a claim, that claim needs to be sourced from something else. "Original research" is a confusing term for this, but it makes a lot of sense once you grok it. From the perspective of an encyclopedia, there isn't much difference between someone's random harebrained theory about cold fusion and a discussion of the lineup of some New York hardcore band nobody's ever heard of outside of NYC.
I think you and I have argued about this before, but I've never understood why "verifiable" isn't the end of the criteria. If the accuracy of information is verifiable through the referenced reliable sources, why should anyone care whether that information is "notable" or not?
Wikipedia's definition of "notable" is simply "significant coverage in reliable sources that are independent of the subject". There isn't a lot of daylight between "notability" and "verifiability".
For instance: someone downthread complained that WP was missing coverage of local bands and an interesting BBC documentary. The BBC documentary should be in Wikipedia, and if it isn't, it's probably because whoever wrote the stub article for it wrote it poorly; someone else should re-add it. But the local bands most likely fail both notability and verifiability: if nobody has written about them, (a) chances are they aren't notable, and (b) whatever is notable about them can't be tied to a specific reliable source, which would make a Wikipedia article about the band original research.
A really common place you run into trouble with Wikipedia is when your proposed article breaks new facts about its subject. That's not supposed to happen. Wikipedia is a tertiary source; if it makes a claim, that claim needs to be sourced from something else. "Original research" is a confusing term for this, but it makes a lot of sense once you grok it. From the perspective of an encyclopedia, there isn't much difference between someone's random harebrained theory about cold fusion and a discussion of the lineup of some New York hardcore band nobody's ever heard of outside of NYC.