Social bookmarking has been one of the famous methods of popularising your blog and I have here a list of the sites which I have come across . This is not the end there are many hundreds out there .

1. del.icio.us
2. stumble
3. furl
4. tailrank
5. diigo
6. digg
7. bluedot
8. slashdot
9. newsvine
10. rawsugar
11. shadows
12. linkagogo
13. excites
14. ma.gnolia
15. kaboodle
16. bibsonomy
17. bookmax
18. plugim
19. oyax
20. citeuluke
21. dzone
22. kinja
23. aboogy
24. bmaccess
25. murl
26. fungow
27. a1-webmarks
28. linksnarf
29. easybm
30. bookmarktracker
31. favoor
32. spotback
33. whitelinks
34. myhq
35. zoogim
36. marktd
37. urlex
38. bukmark
39. searchles
40. whitelinks
41. putvote
42. lilisto
43. sitejot
44. shakk.us
45. connotea.org
46. chaamp
47. blurpalicious
48. mywebdesktop
49. chipmark
50. gabbr
51. cloudytags
52. buddymarks
53. corank
54. de.lirio.us
55. faimous
56. fark
57. listible
58. rollyo
59. thoof
60. yahoo
61. mybloglog
62. stories.swik.net
63. icerocket
64. myvmarks
65. itaggz

I will update as and when I come across new ones happy social bookmarking