OPTIMISTIC
Radiohead

DROPPED-D TUNING 
no bass during the first two times a verse is sung.

*RIFF #1 The bass comes in quietly at 1:07:
G----------------------------------------------|x2
D----------5-----------------------------------|
A--------------5---3h5-5-5-x-x-3h5-5-5--5-5--5-|
D--0---0---------------------------------------|

During the interim between the first refrain and second verse:
G---------------------------------|
D---------------------------------|
A-----5--3h5-5-5-----5--3h5-5-5---|
D--0--------------0---------------|Repeat until 2nd verse

Repeat Riff #1 during the second refrain. Then, at 2:32:
*RIFF #2
G--------------------------------------------|x4
D--------------------------------------------|
A--7h8-8-8--8h7-7--7--9h10-10-10--10h9-9--9/-|
D--------------------------------------------|

During the third semi-verse, just thumb the low D-string:
G--------------------------------------------|
D--------------------------------------------|
A--------------------------------------------|
D--0-0-----0-----0-0-----0-----0-0----0------|

Now, repeat Riff #1, then play Riff #2 with slight variation 
on the second repetition:
G--------------------------------------------------|
D--------------------------------------------------|
A--7h8-8-8--8h7-7--7--9h10-10-10--10-10--9/12-12/5-|
D--------------------------------------------------|

On the fourth repetition, leading to the outro, play this:
G--------------------------------------------------------|
D---------------------------------------------12h10------|
A--5-7-7h8-8-8--8h7-7--7--9h10-10-10--10h9-9-------12h10-|
D--------------------------------------------------------|

The first part of the outro features improv on high D:
G--------------------------------------------------------|
D-0--12--0-10-0-10-10--12/0--12-0-10-12-12/0--3-/-5-5--4-|
A--------------------------------------------------------|
D--------------------------------------------------------|
You can also hit the 7th fret and bend the 12th if you like.

The final part of the outro is light and jazzy, and goes:
G--------------------------------------------------------|
D-0-12-0-10-10-0-12--0-0-----10-0-12-0-10-10-0-12--0---0-|
A-------------------------10-----------------------------|
D--------------------------------------------------------|