I can see that. In any case, there a million Youtube videos of popular geek material mutated through Miku, which I found quite entertaining, not to mention adorable. If the Mario Paint Composer remixes are considered a form of meme (I'm not sure if they are), then I suppose Vocaloid remixes would count, as well.
Here's a few of the videos I came across while researching on Youtube. Check the related content, there's tons of stuff.
Hatsune Miku sings:
"THIS IS SPARTAAA!!": https://www.youtube.com/watch?v=NTtifcooH58
Still Alive: https://www.youtube.com/watch?v=12b6Om758Q (Uh, there's a link at the bottom, for some reason this is broken)
Levan Polkka: https://www.youtube.com/watch?v=kbbA9BhCTko
Caramellodansen Remix: https://www.youtube.com/watch?v=KmVZTEIabgg
Fly Me to the Moon: https://www.youtube.com/watch?v=YUpIjWAWDuQ
Angry Video Game Nerd theme: https://www.youtube.com/watch?v=9DTejtOPE1o
Pokemon Red & Blue theme: https://www.youtube.com/watch?v=9DTejtOPE1o
FF4's 'Within the Giant': https://www.youtube.com/watch?v=Vjux8nupR9w
The Mario theme song: https://www.youtube.com/watch?v=CfSnrozj4iI
An NES medley: https://www.youtube.com/watch?v=JkcjJNgWTr8
Castlevania 2 medley: https://www.youtube.com/watch?v=o7LjhRRvxs (This one broke, too, fine at the bottom.)
Legend of Zelda medley (sounds stranger than most): https://www.youtube.com/watch?v=JN-o4uNdIT8
Megaman 2 – Wily Stage 1: https://www.youtube.com/watch?v=0sa7QcxxSnE
A portion of Megaman 3, complete with sound effects: https://www.youtube.com/watch?v=3yIao9fr1BQ
Sonic medley: https://www.youtube.com/watch?v=BuF28Dqcwec
As for the actual character, I've got a feeling she's all over the place in Japanese websites and forums, but I don't know where to start, as I'm unfamiliar with the territory altogether.
These videos hint at a bigger picture in memedom on the Eastern front, though they're pretty inconclusive on their own:
"Hatsune Miku Parody" – https://www.youtube.com/watch?v=ojwrqHTSYw4
Hatsune Miku vs. Nico Nico Douga – https://www.youtube.com/watch?v=zXsrRLT2ijs
And a small documentary on the whole phenomenon:
https://www.youtube.com/watch?v=xBZOlipfjkQ
If anyone knows the final boss of the internet that is Japanese websites, I'd appreciate some research into the matter.
EDIT: Still Alive: https://www.youtube.com/watch?v=_12b6Om758Q
Castlevania 2 Medley – https://www.youtube.com/watch?v=o7LjhRR_vxs
EDIT EDIT: Further research yielded more conventional memage.
Umbrella feat. Hatsune Miku: https://www.youtube.com/watch?v=H54pdkB2bkU
We Will Rock You: https://www.youtube.com/watch?v=O9496NyP-c4
Don't Worry, Be Happy: https://www.youtube.com/watch?v=7MRFh3eX1nU
Miku dancing in Smooth Criminal: https://www.youtube.com/watch?v=Pu18cpBGczo
Miku Dancing the Billie Jean dance: https://www.youtube.com/watch?v=7934elDPjbI
The Matrix Reloaded Agent Smith Clone Fight Scene: https://www.youtube.com/watch?v=cjCFH4TTJRA (Fast forward to 4:50 unless you really like Japanese dialogue)
Sumo wrestler Miku: https://www.youtube.com/watch?v=MA2KG2M-h1I (?)
Miku in… Er… Some wrestling game that's really popular in Japan: https://www.youtube.com/watch?v=sWmdzUcyJA8
I'm not even sure what to make of this one, I WTF'd the whole time: https://www.youtube.com/watch?v=YKstpZ-JFSc – But this is just a reminder of the possible meme status of Vocaloid in Japan.
Miku singing Phantom of the Opera: https://www.youtube.com/watch?v=vPmAFyoGO50
Miku singing I'm Gonna Be (500 Miles): https://www.youtube.com/watch?v=E6m2NzdN7o0
Miku singing Heaven is a Place on Earth: https://www.youtube.com/watch?v=HATpOha7DFg
Miku and friends sing Pachelbel's Canon: https://www.youtube.com/watch?v=COfSoBHE2Xk
An original song based on Yukkuri Shitiette Ne: https://www.youtube.com/watch?v=0k7ERlE96PA&
A collection of national anthems: https://www.youtube.com/watch?v=muPQ7hwEYvk
Kirby Green Greens: https://www.youtube.com/watch?v=T-IXZGQ1i-U
Bananarama's Love in the First Degree: https://www.youtube.com/watch?v=aZa2qNUptHY
Well this one is ultrawin. Miku Astley: https://www.youtube.com/watch?v=J_tBou4juBs
I will edit this post to put in new videos. For the sake of research completeness, this may become a rather long list.
I think I'm done for now (combo breaker and whatnot). These are all the ones that stuck out to me in the last ~three hours. The amount of content on Youtube alone is rather staggering. I'm hesitant to call Miku a "meme", strictly speaking, at this stage of research, but I think the Vocaloid project itself has caught on like wildfire, and been used for a wide variety of purposes. It's up to you guys to make the call, though. What do you think?