jwschang said:(Waiting for people) can be quite vexing. (Participle phrase as Noun).
I would think it's a Participle phrase serving as a Noun phrase. It's not a gerund because a gerund is the Continuous Participle used as a noun. In that sentence, while the phrase itself serves as a noun, the word "waiting" is used as a participle and not a noun WITHIN the phrase.
I'm way lost.
Waitingcan be quite vexing = It can be vexing.
Participles functioning as subject and objects are called gerunds.
It's still not clear to me, though, how it can function as an adjective. I'm interested in learning this new function. Could you offer some insight.