Since I so enjoy this list making, I thought to research what people are paying for ads regarding keywords.  I started with:

• keyword
• keywords
• keyphrase
• keyphrases

and got this list:

1. keywords - $0.27
2. keyword - $0.27
3. keyphrase - $0.06
4. keyword billing - $0.10 - I don’t know what this is.
5. keyword density - $0.55
6. keyword search - $0.55
7. keyword tool - $0.55
8. keyword generator - $0.55 - I’m noticing a trend here.
9. keyword marketing - $1.46
10. meta tags keyword - $0.55
11. keyword extractor - $0.10
12. keyword tracking - $0.54
13. internet keyword - $0.55
14. keyword bids - $0.23
15. keyword list - $0.52
16. keyword popularity - $0.21
17. top keywords - $0.20
18. aol keywords - $0.10
19. keyword traffic - $0.10
20. keyword rankings - $2.64
21. keyword lists - $0.52
22. keyword density analyzer - $0.55
23. keyword suggestor - $0.10
24. top search keywords - $0.11
25. keyword search engine - $0.55
26. overture keyword - $0.35
27. top 100 keywords - $0.10
28. keywords search
29. keyword advice
30. keyword seo - $0.10
31. keyword service - $0.11
32. meta keyword
33. keyword relevancy - $0.15
34. get keywords
35. html keyword
36. overture keyword tool
37. keyword analyzer
38. keyword research tool
39. keyword suggestion tool
40. keyword checker
41. meta keywords
42. google keyword
43. aol keyword
44. keywords software - $0.351
45. google keywords
46. keyword selector tool
47. keyword research
48. overture keywords
49. adsense keywords
50. resume keywords
51. keyword ranking
52. keyword help
53. good keywords
54. overture keyword suggestion
55. find keyword
56. keyword analysis
57. overture keyword selector
58. keyword name
59. keyword assistant
60. keyword searches
61. overture keyword suggestion tool
62. by keyword
63. keyword tracker
64. keyword searching
65. high paying keywords - $0.10
66. overture keyword search
67. search engine keywords
68. best keywords
69. google keyword tool
70. keyword density tool
71. most searched keywords
72. yahoo keyword
73. keyword bible
74. keyword search tool
75. chinese keywords
76. keyword stuffing
77. keyword software
78. keyword optimization
79. google keyword stuffing
80. overture keyword selector tool
81. highest paying keywords - $0.10