Does your website have a custom 404 error page? If not, you have many examples to choose from.
404 Error Pages
1. Wufoo
2. Mixx
3. Student Market
4. Cartoon Network
5. Daze of Our Lives
6. Jamie Huskisson
7. Suspended Animations
8. Galiacho
9. Homestar Runner
10. Radiohead At Ease
11. Slonky
12. PrintScreen
13. Martin Korner
14. Aviation Reviews
15. Jackfig
16. Pen and Paper
17. Acro Media Inc
Carry The Duck
19. The Big Noob
20. Apple
21. Technorati
22. Twitter
23. Scythe
24. The North Face
25. Spore
26. Digg
27. Social Thing
28. Product Planner
29. BrightKite
30. The New Yorker
31. Mozilla
32. Sunny Side of truth
33. Frye / Wiles
34. Pattern Tap
35. Fuelly
36. The Web Motel
37. CUOMA Design Studios
38. euh?
39. Homestar Runner
40. Mark Fennell
41. Limp Fish
42. Github
43. Total Insanity
44. LILEKS
45. South Park Studios
46. The Official Dilbert Website
47. Clear Spring
48. The Hypertext d20 SRD
49. Dawdle
50. GeekSquad
51. DDZ
52. Warhammer Online
53. Jotsai
54. Enlighten Designs
55. UrbanOutfitters
56. G4
57. Ma.gnolia
58. Unit Interactive
59. Chris Glass
60. LeafQueen
61. Kitty-Yo
62. Renkoo
63. DanBailey
64. Amorphia Apparel
65. ACME Laboratories
66. Hasbro Network
67. Fisher-Price
68.
69. deviantART
70. JSOnline
71. Soocial
72. The Brand Surgery
73. Space Ninja
74. Gimme! Coffee
75. Trinicom Communications
76. Craigslist
77. Daniel Karcher
78. Center’d!
79. Abduzeedo
80. Cats Who Code
81. Tele2 Norge AS
82. Retard Zone
83. Zanami
84. Kidmondo
85. Turbomilk
86. iFolderLinks
87. CSS-Tricks
88. Propeller
89. Expansion Broadcast
90. Dropbox
91. Attrition
92. Adobe
93. Libria
94. MundoFox
95. F23
96. Design Shuffle
97. MOO
98. Mixtapes from Pukka Dawn
99. Arbitrary Constant
100. Boagworld
101. Take Off Eh!
102. Dbatesworld
103. NYC Bike Maps
104. KiGOE
105. Ministère de la culture et de la communication
106. Orange Coat
107. Made by Michelle
108. Lightpost Creative
109. Deaxon
110. Vudumedia
111. Craptastic
112. Incan
113. Lego
114. SodaHead
115. The Sun
116. Cubeecraft
117. RaidenHTTPD
118. Shelfworthy
119. Disney
120. Active Ride Shop
121. Heinz
122. BrightKit
123. Wakoopa
124. PostRank
125. Tyson Tate
126. Book golf times in the UK
127. Mac OS X
128. Function
129. MephoBox
130. Duoh
131. Emptees
132. Morphica
133. Late Late Gifts
134. Designzillas
135. Kochatelier Berlin
136. Henrik Hedegaard
137. Zivity
138. BargainJack
139. Trenton Computer Festival
140. Scribbls
141. Ning
142. Laughing Squid
143. SproutCore
144. Kottke
145. NextWave Performance LLC
146. Porcupine Colors
147. Malted/Media
148. Elixireleven
149. MailChimp
150. Meebo
151. Squidoo
152. CafePress
153. Internet Shakespeare Editions
154. Lookitsme
155. Red Bull Energy Drink
156. Marvel
157. A List Apart
158. cgCraft LLC
159. Chevron
160. Twingly
161. eToys
162. Netvibes
163. Rainfall Daffinson
164. CSS Ninjas
165. Sonic
166. VintFalken
167. John Fanzine
168. CSSRemix
169. Nokia
170. Coca Cola
171. Wulffmorgenthaler
172. Groovy Web Design!
173. Digiguru
174. Springload
175. Apartment Home Living
176. Carsonified Events
177. PockyWorld
178. Reddit
179. ConflictZen
180. LinkHay
New one:
http://www.webogroup.com/404/