The top right bar on this site only allows a four letter minimum. These are some of the most popular words I found:
Create - 153
Search - 145
Title - 140
Window - 138
Google - 136
Fall - 134
Company - 133
Comment - 132
Mouth - 130
Summer - 129
Nerd - 128
Safe - 124
Christ - 123
Gaming - 123
Hell - 123
Amazon - 122
Members - 122
Netflix - 122
Fire - 119
Thread - 118
Trip - 118
Bored - 117
Facebook - 117
Girlfriend - 114
Part - 114
Blue - 112
Boys - 112
Computer - 112
Hand - 112
Life - 112
Closed - 111
Hero - 110
Saved - 110
Year - 110
Party - 109
Fuck - 107
American - 106
Fish - 106
Photo - 106
Gold - 105
Jesus - 105
Keyboard - 105
Woman - 105
Amazing - 104
Boyfriend - 103
Cartoon - 103
Green - 103
Head - 102
Mario - 102
Dogs - 101
*If anyone still uses this site and wants to play along, feel free to post words that have been used over 100 times that I forgot to mention.