The seven spirits of God (including the Holy Spirit?)

I beheld ... a Lamb as it had been slain, having seven horns and seven eyes, which are the seven Spirits of God. Revelation 5:6

The book of Revelation is obsessed with the number seven. God's magic number is used 52 times in 30 verses, with 19 things grouped into sevens.

But the most interesting grouping is the number of God's spirits. Who knew that he had seven of them?

Here's the whole crazy list, with links to the verses so you can read them in context (like that would help or something).

1	churches of asia	1:4, 1:11, 1:20(2)
2	spirits before God's throne	1:4
3	golden candlesticks	1:12, 1:13, 1:20(2), 2:1
4	stars in the Jesus' right hand	1:16, 1:20, 2:1, 3:1
5	angels	8:2, 8:6, 15:1, 15:6, 15:7, 15:8, 16:1, 17:1, 21:9
6	spirits of God	3:1, 4:5, 5:6
7	lamps	4:5
8	seals	5:1
9	horns	5:6
10	eyes	5:6
11	trumpets	8:2, 8:6
12	thunders	10:3, 10:4(2)
13	thousand people killed in an earthquake	11:13
14	heads	12:3, 13:1, 17:3, 17:7, 17:9
15	crowns	12:3
16	plagues	15:1, 15:6, 15:8, 21:9
17	golden vials filled with the wrath of God	15:7, 16:1, 17:1, 21:9
18	mountains	17:9
19	kings	17:10