Vowels !?!?!?!

How many vowels are there in English?  How many vowel sounds are there?  How many ways are there to spell those vowel sounds?  Below is a game that my siblings and I have played for years.  It's rather simple... or should be. :)

simple
Raid, read, ride, rode, rude
Lane/lain, lean/lien, line, loan/lone, loon/lune
Sack, sec, sick, sock, suck 
Panned, penned, pinned, pawned, punned

works with both long and short
Bat, bet, bit bought, but/butt
Bait, beat/beet, bite/byte, boat, butte/beaut/boot (which long "u" sound to you want to use?)

a bit more complex
Cane/Cain, keen, kine, cone, coon

excuse me?!?
Gnat, net, knit, not/knot/naught, nut

There are MANY others.  Feel free to think of them and add them as comments... don't bother adding the "almosts"; there are too many to count.