There are a ton of great shortcuts in Lightroom. Below you will find a few that I have found most useful. Enjoy!
If you are interested in an overview (with a few shortcuts) of Lightroom - click here

If you are interested in the screen grabs of the Lightroom shortcuts - click here

If you are interested in viewing all the shortcuts on Adobe's site - click here

General

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L = Lights Out
F = Fullscreen Modes
E = Loupe
G = Grid
D = Develop
R = Crop
Command/Cntrl + [ ] = Rotate
Command/Cntrl + R = Locate in Finder
Command/Cntrl + E = Edit in Photoshop
Shift + Command/Cntrl + E = Export
0-5 = star rating
6-9 = label
Command/Cntrl + K = Keyword
Command/Cntrl + F = Find
Shift + Command/Cntrl + I = Import
Command/Cntrl + Return = Slideshow
F5, F6, F7, F8 = these F keys show or hide the interface
Tab = Show/Hide Panels
Shift + Tab = Show/Hide Everything
Command/Cntrl + L = Enable Filter

Library

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F2 = Rename
Option/Alt + Delete = Delete without dialogue window
C = Compare (2 images)
N = Survey ( Multiple Images)

Develop

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Show Clipping = J
Show/Hide Tool Bar = T
Spot Healing = N
White Balance = W
Shift + Command/Cntrl + R = Reset all (raw settings)
Shift + Command/Cntrl + C = Copy Raw Settings
Shift + Command/Cntrl + V = Copy Raw Settings
V = Convert to Grayscale
Shift + Command/Cntrl + U = Auto White
Command/Cntrl + U = Auto Tone
Command/Cntrl + 1-7 = select panels (Basic, Tone Curve, HSL, etc.)