Cameos and Homage: Good or Bad?

[Mystic Mage]

I was wondering what people's thoughts were on cameo appearances and homage to games within a game.

What are some pros and cons? What is best to avoid? What are some desirable scenarios?

I don't plan on doing this much if at all in the game I want to make, but I thought I'd ask to get a few opinions.

[Holyrapid]

Well, i think it's a nice idea if done well. Good example would be something like a NPC mentioning the game, saying that he like's the game, or have a character model as a one time NPC or something like that.
Bad example: Showing it to the players face, like having a million copies of the games logo spread in the game...

[The Niche]

If your game's set today, it's fine to have people mentioning the game. If it's another time, you're best off just going with having an npc there.

Take care though. Cameos will remind the player of another game, which will in turn remind them they are playing a game. It'll create positive emotions in the player, as long as it's kept to no more than one or two.

[brewmeister]

Good if it's done to support your story / plot.
Bad if it's done just for the sake of doing it.
Although I suppose the comedic effect of Mario walking by & asking, "Hey, have you seen a princess? Tall... Blond... last seen with a big monkey???" would get a laugh. In moderation though.

[Mystic Mage]

Good points from all three of you. I'll try to keep those things in mind.
Actually, having a NPC or two was the one thing I was thinking of doing.
Specifically, I'd like to have Neko and Niccolo, from Secret of Mana and Legend of Mana respectively, to show up now and again to sell the main character some items. I am only considering this though, and might not implement it.
Even if they did show up, there will be many other merchants so they will not take the spotlight or anything.