You should be also be aware of the unfavorable changes that DL is instituting and imposing on its FF'ers in Skymiles.

There is also a brand new website at
www.saveskymiles.com

Take a look and see if you may want to be a part of the ongoing efforts to try to reverse
these DL changes. Changes at one carrier now are very likely to be cahnges in another soon!
http://www.flyertalk.com/forum/Forum21/HTML/001505.html