Many of these sites offer international stores, which I tried my best to include in the listings.  Usually I was able to find the international variants of these stores at the bottom (or footer) of the page.

1. [CANADA] http://pricecanada.com
2. [NETHERLANDS] http://www.kelkoo.nl/
3. [USA] http://shopping.com
4. [BELGIUM] http://fr.kelkoo.be/
5. [USA] http://pricerunner.com
6. [UK] http://www.pricerunner.co.uk/
7. [CANADA] http://pricenetwork.ca
8. [CANADA] http://redflagdeals.com
9. [CANADA] http://craigslist.com
10. [CANADA] http://kijiji.com
11. [CANADA] http://shopbot.ca
12. [CANADA] http://pricegrabber.ca
13. [CANADA] http://shoptoit.ca
14. [UK] http://kelkoo.co.uk
15. [FRANCE] http://www.kelkoo.fr/
16. [SPAIN] http://www.kelkoo.es/
17. [ITALY] http://www.kelkoo.it/
18. [NORWAY] http://www.kelkoo.no/
19. [SWEDEN] http://www.kelkoo.se/
20. [GERMANY] http://www.kelkoo.de/
21. [DENMARK] http://www.kelkoo.dk/
22. [FRANCE] http://www.pricerunner.fr/
23. [GERMANY] http://www.pricerunner.de/
24. [AUSTRIA] http://www.pricerunner.at/
25. [SPAIN] http://www.pricerunner.se/
26. [DENMARK] http://www.pricerunner.dk/
27. [CANADA] http://photoprice.ca (Cameras Only)
28. [USA] http://www.shopzilla.com/
29. [USA, UK, AUSTRALIA] http://www.quickshop.com/
30. [AUSTRALIA] http://www.shopwiki.com.au/
31. [USA] http://pricegrabber.com
32. [USA] http://www.nextag.com/
33. [UK] http://www.nextag.co.uk/
34. [FRANCE] http://www.nextag.fr/
35. [GERMANY] http://www.nextag.de/
36. [USA] http://www.mysimon.com/
37. [USA] http://www.bizrate.com/
38. [UK] http://www.bizrate.co.uk
39. [FRANCE] http://www.prixmoinscher.com/
40. [USA] http://www.streetprices.com/
41. [USA] http://www3.dealtime.com/
42. [USA] http://www.pricescan.com/
43. [USA] http://www.order.com/
44. [USA] http://www.shopwiki.com/
45. [UK] http://www.shopwiki.co.uk/
46. [FRANCE] http://www.shopwiki.fr/
47. [CANADA] http://www.pricebat.ca/
48. [UK] http://www.twenga.co.uk/
49. [FRANCE] http://www.twenga.fr/
50. [GERMANY] http://www.twenga.de/
51. [SPAIN] http://www.twenga.es/
52. [ITALY] http://www.twenga.it/
53. [POLAND] http://www.twenga.pl/
54. [NETHERLANDS] http://www.twenga.nl/
55. [BRAZIL] http://www.twenga.com.br/
56. [RUSSIA] http://www.twenga.ru/
57. [USA] http://www.pricewatch.com/
58. [UK] http://www.beatthatquote.com/
59. [UK] http://www.comparestoreprices.co.uk/
60. [UK] http://www.priceinspector.co.uk/
61. [USA] http://www.justboughtit.com/
62. [USA] http://www.smarter.com/
63. [CHINA] http://www.smarter.com.cn/
64. [JAPAN] http://www.smarter.co.jp/
65. [KOREA] http://www.smarter.co.kr/
66. [USA] http://www.kaboodle.com/
67. [AUSTRALIA] http://www.getprice.com.au/
68. [USA] http://www.beatmyprice.com/
69. [UK] http://www.ciao.co.uk/
70. [GERMANY] http://www.ciao.de/
71. [FRANCE] http://www.ciao.fr/
72. [ITALY] http://www.ciao.it/
73. [SPAIN] http://www.ciao.es/
74. [NETHERLANDS] http://www.ciao-shopping.nl/
75. [SWEDEN] http://www.ciao.se/
76. [USA] http://www.ciao.com/
77. [AUSTRALIA] http://www.shopbot.com.au/
78. [UK] http://uk.streetprices.com/
79. [CANADA] http://ca.streetprices.com/
80. [IRELAND] http://ie.streetprices.com/
81. [UK] http://www.icoste.com/
82. [UK] http://www.become.co.uk/
83. [UK] http://www.lesslettuce.co.uk/
84. [BELGIUM] http://www.beslist.be/
85. [FRANCE] http://www.codespromotion.fr/

77 sites, from as many countries as I could find (hey, China and Japan are a lot more rare than you think).  Hope that they work well for you, and never, ever, again, make you pay full price for that iPod.

Update [2/24/2009]: I know I’ve got up to 80 now, I originally didn’t find the Streetprices.com International sites.