Jimmy Page has posted a mashup of Led Zeppelin's "Ramble On" with Notorious B.I.G.'s "Hypnotize" and it's pretty cool. Check it out by clicking on the link above. It's a private SoundCloud file, so that's the only way you can hear it right now. At one point it was streaming at JimmyPage.com, but it appears that's changed.
You can hear that Page adjusted the vocal timing of "Hypnotize" to fit Zeppelin's "Ramble On" and it sounds great. Hopefully we get more interesting stuff like this from him in the future.
If you like this, check out the "Whole Lotta Sex Machine" mashup of Led Zeppelin with James Brown.