Sometimes there is a guitar riff that just friggin’ grooves. It makes you tap your foot, or bang your head. It moooooves you!
I will put forth 2.
“Killing in the Name” by Rage Against the Machine. The groove that drops in at :41 just kills.
The other, which may require me to be charged 10 “cool demerits” is “Hazy Shade of Winter” as covered by the Bangles. The groove that comes in at :30 completely drives the song.
So - what grooves move you?
I would nominate “Stay As You Are” by Span. That riff kicks all kinds of ass.
John McGeoch (Siouxsie and the Banshees, Armoury Show, P.I.L.) was a riff master beyond compare.
Nile Rodgers does well in this department, and not surprisingly, Andy Taylor of Duran Duran has some killer riffs no doubt greatly influenced by Mr. Rodgers.
The one I always think of first is Just One Fix by Ministry.
My other choice would be something by the Deftones but I can’t decide which one. One of their earlier songs at any rate.
That song is just flat-out relentless. Crushingly relentess. 
In a very good way.
But not what I would offer here - it lacks groove. For metal grooves, I would be much more inclined to go with **Sad But True **by Metallica or **Walk **by Pantera. Both feature behind-the-beat, groove-y drums…
But listing guitar grooves? Oy - such a task. I would have to start back with T-Bone Walker’s Strollin’ With Bones, or some early Robert Johnson, Charlie Patton and Memphis Minnie, all the way up through today - with a major pitstop in the land of Chuck Berry!
The Rolling Stones’ Beast of Burden is one of the groovin-est guitar parts ever.
Black Sabbath built a career (and a genre) on Iommi’s groovy guitar genius.
“Don’t Fear the Reaper.” I’ve always thought that BOC blundered into the groove and then wrote the (okay, but not particularly great) song around it. Same deal with “Smoke on the Water.”
“The One I Love” by R.E.M
“Ticket to Ride”
“Cinnamon Girl”
Oh boy, grooves! Here’s some of my favorite metal grooves, mostly in alphabetic order since I want to find the times:
Cephalic Carnage - Divination & Volition @ 3:10 - I never liked grindcore until I heard THAT riff; still the only grind band I like though.
Moonspell - Finisterra - I won’t bother with a time here since it’s the main riff and it repeats several times during the song. I defy anyone not to want to bang their head to this song.
Nevermore - Deconstruction @ 1:47 - This is actually one of their weaker songs IMO, but I’ll be damned if that isn’t one hell of a groovy riff.
Nevermore - Never Purify @ 0:23 - This is perhaps the grooviest riff of the bunch here. Jeff Loomis just does some sick guitar grooves and his solo project is pretty much just an hour straight of stuff like this.
Opeth - Deliverence @ 0:25 - Another band that just has tons of awesome grooves that set the tone. There’s a few other good ones later in the song too.
Opeth - Heir Apparent @ 1:20 - One of my current favorites and a pretty good groove too.
Swallow the Sun - The Giant @ 3:48 - One of the best riffs I’ve ever heard, flat out; it’s a pretty sick groove too.
Eh… that’s enough for now.
Back in Black - AC/DC
If Beast of Burden is a contender, you’ve got to include Brown Sugar.
And just about anything by Chuck Berry.
“Day Tripper”
“Superstition”, man.
What you’re hearing in *Superstition *is not a guitar. I think it’s a clavinet, although I could be wrong.
Yep, it’s the Clavinet C.
I thought about piping up with that, but since it was originally written for Jeff Beck who recorded a version using guitar, I kept quiet…
Maybe Zsofia’s thinking of the Stevie Ray version? In which case, I think it just might qualify.
For my money, Back In Black (already mentioned) has a huge groove going on - seriously, the space between the notes in the opening riff are freakin’ epic. Oddly enough, it gets slightly less groovy when the drums kick in, perhaps because Phil Rudd plays like a metronome since Bon died.
Which is odd, because many of the best guitar grooves are only as groovy as they are because of the rhythm section behind them.
ETA: Or not - I just realized that statement answers its own question. 
Cool Number 9 - Joe Satriani (Actually most of his work, to be honest)
Red Barchetta - Rush (Alex Lifeson is one of the more underrated guitar gods, IMO)
Glasgow Kiss - John Petrucci (Dream Theater) http://www.metacafe.com/watch/yt-2YWXpHl9sGk/john_petrucci_glasgow_kiss_demonstration/
Whoo hoo. I’m a bit pissed, but since Wordman has posted I feel bound to post something:
http://vodpod.com/watch/1127574-the-black-crowes-wjimmy-page-custard-pie
Mr Page un underated(?!) rhythm guitarist.
SC posting from a hotel, it’s grim up north (but we get WiFi)
submitting tho’ I should know better.
I don’t know if groove is the right word, but Johnny Marr’s iconic guitar playing on How Soon is Now? is just driving the song.
The groove underneath the last half of the solo of “Rock 'N Roll Hoochie Koo” is way cool…
Also, the ending of “It’s A Long Way To The Top” by AC/DC, underneath the bagpipes…