I finished reading The Electric Meme by Robert Aunger. He presents a coherent theory on memes that doesn't involve them spontaneously jumping from brain to brain (or artifact to brain), which is a great relief as meme theory is very interesting and I have no intention of amending my beliefs to include the existence of things like ether[0] in order to justify perusing an interesting theory.
The book isn't so much a definitive statement on what memes are, but rather is a good first step in knowing where to look for them when our technology is sufficient to physically analyze the human brain.
I'd give it a 4/5 and say it's definitely worth reading if you're interested in meme theory.
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[0] Webster's Dictionary: "ether 1 a : the rarefied element formerly believed to fill the upper regions of space". Not that stuff you use to connect your computer to your router, I believe in cat5.