Crazzee said:
The technical definition of a meme is "Any unit of cultural information, such as a practice or idea, that is transmitted verbally or by repeated action from one mind to another. Examples include thoughts, ideas, theories, practices, habits, songs, dances and moods and terms such as race, culture, and ethnicity." Now, as most of us know, many memes start and end at 4chan, such as An Hero, LOLcats(I think), and all that Snakes on a Plane stuff.
I disagree with your definition of meme. Well, actually, your definition isn't bad, but your examples are. Memes are big ideas. Religion, politics, concepts. LOLcats, Rickrolling, etc. are extremely limited individual in-jokes/ideas. Look at your definition, and then your examples. Snakes on a Plane is not a thought, idea, theory, practice, habit, much less an invented, far reaching idea like race, culture or ethnicity.
Are memes good or bad? Depends on the meme, what is done with it, and who is witnessing the result.
If you're specifically looking at so-called "internet memes" and simply referencing them as the larger concept of memes, then I'd say the answer is that they act as a form of community building whereas those in the know enjoy the shared experience of knowing what the hell it is that can then become an annoyance when the internet meme becomes so pervasive that it loses its ability to mark a subgroup - if everyone on the planet gets it, it isn't so amazing that you do.