Please Help Me Find Some Keys

No..not my car keys. :) I just started singing in a blues group. During our first practice we found out which keys were better for me, for a couple of the songs. The problem is I don't know which keys the songs were in originally. I'm a good singer, but I never learned to read music.

The songs are Spoonful (this version here): http://www.youtube.com/watch?v=6TwEYuues6Y

Got My Mojo Working (this version:)
http://www.youtube.com/watch?v=hjPezeHN9Hc

Built For Comfort (this version:)
http://www.youtube.com/watch?v=kkv8e6aUcxc

and Smokestack Lightnin (this version:)
http://www.youtube.com/watch?v=kAwjZLztd28

I know I could email the members of the band, but...I'm trying not to look as newbish as I truly am. Thanks in advance for your help, folks.

well, You seem to up for good music :P.

I think spoonful is an key of E

Mojo working = A

Built for comfort is hard for my ears :) Its sounds like G but dun sure

smokestack is a bit tricky, but I think its E

Im not very good at figuring out keys, but others may correct if im wrong.