Clips:
Spirit – “Taurus” (1968)
The Chocolate Watchband – “And She’s Lonely” (1969)
Led Zeppelin – “Stairway to Heaven” (1971)

More about Page and his borrowing activities here.

Update, 5/21/14: Spirit will now be taking Zeppelin to court over this, which is a shame. A descending guitar figure is not substantial creative property and the two songs are otherwise very different. Time and money will be wasted and the beautiful “Taurus” will be tainted, regardless of the outcome.