For me it's Gimme Shelter by the Rolling Stones



I also like She sells Sanctuary by the Cult (long version) and Do anything you wanna do by Ediie and the hot rods.



As for riffs, to many to choose from.

90% of Northern Soul tracks including:

Bari Track - Doni Burdick

Can you hear me knocking by the Rolling Stones

Stay With Me by the Faces

5:15 by the Who

Carry On by Crosby Stills and Nash

Fresh Garbage by the Spirit

Roadhouse BLues by the Doors

For those about to Rock ACDC

Reelin in the Years by Steely Dan

Pump it Up Elvis Costello

there are way too many to mention

Back in black AC/DC

its a long way to the top if you wanna rock'n'roll AC/DC

Iron man Black Sabbath

smoke on the water Deep Purple

Forgot

The Trooper Iron Maiden

good choice, i will add to that Powerslave, Women in uniform & Moonchild

Radiohead - Just (Also has a very impressive outro too!).

And despite some of you mentioning The Who, nobody mentions:



Baba O'Riley



Best intro of all time

Magazine -shot by both sides .

Mt Abraxas (by Uncle Acid & the Deadbeats) - about 4.5 minutes in a massive doom riff kicks in for about another 2 minutes solid. I think its the riff of the decade. It basically out-sabbaths sabbath if you know what I mean.

Second best, Gimme Shelter is better

So come on by The Atomic Bitchwax has a kick ass riff, also Evil eye by Fu Manchu