Am using BlogEngine.NET (open source) for this blog. If you are also using the same engine for your blog and if you are searching for some themes, you can find some themes i wrote below
1. Premium – A 3 column template
2. illacrimo
3. 4 Templates (Dark Ritual, Did_My_Time, Global, Shades Of Gray)
Now here is a collection of 70 BlogEngine.NET Themes, which you can download as a zip file from BlogEngine.NET Themes on Codeplex.
the themes included are the following
1. angel
2. aquaria
3. Automotive
4. BibleScholar
5. BluePigment
6. brightside
7. BusinessTime
8. Clarity
9. ClearBrown
10. CoffeeHouse
11. Cogitation
12. CuriouslyGreen
13. DarkBlog1.0.0
14. Darkside
15. desk-mess
16. dilectio
17. Dirtylicious
18. Discovery
19. eco
20. Envision
21. EvilCorporate
22. Extensive
23. Fresh
24. freshcitrus
25. fruity
26. funkygrunge
27. GardenBee
28. GirlGeek
29. Gluttony
30. GreyShadow
31. i3Theme
32. illacrimo
33. Indigo
34. inove
35. Interlude
36. iPhone
37. iTheme
38. LayoutGala
39. LCARS
40. Leaves
41. LiquidNautica
42. MarketPlace
43. MsdnStyle
44. MWRT-002
45. NaturalEssence
46. Newspaper
47. NFL.1.0
48. NonZero
49. notepad-chaos
50. oldschool
51. Paalam
52. Paperclip-Cactus
53. portraitpress
54. ProfessionalLight
55. RoyalBlue
56. SapiensNet
57. Scruffy
58. SilverLight
59. StableStart
60. stardust
61. Stargazer
62. SwanDive
63. TechJunkie
64. Terrafirma
65. TheGreenHouse
66. Triathlon
67. Underwater
68. unqualified
69. vertigo2
70. WildNature
You can download them from here