You can also look into Iron Mountain. They do offsite tape storage and automatic back ups. I would guess they do DR also. kacerc
Check out www.SunGard.com Have used their services in the past. They have great facilities and very knowledgeable people.
IBM also has a DR facility outside Chicago depending on the size of your iSeries that you need to recover. They also have other hardware for DR recovery and offer mirroring services.
Both SunGard and IBM have very complete sites with very skilled people.
I know there are some smaller hosting companies but I do not know there names and if any are in the Midwest.