Currently Being ModeratedJan 3, 2013 5:23 PM (in response to CJeremy)
Unfortunately you will not be able to back up from iPhone to iPhone.
(This is assuming you're using iTunes 11)
There is the possibility of backing up to your husbands Mac, however like ckuan mentioned it can mix up information. The best way to avoid this is by selecting iTunes in the taskbar along the top (next to the Apple Logo), select Preferences, select Devices from the options along the top. Towards the bottom you will see an option stating "Prevent iPhones etc... from syncing automatically.", make sure this box is ticked as this will prevent the iPhone from syncing automatically, therefore preventing it from mixing up yours and your husbands information.
Here you can connect the iPhone.
The next step would be to select File from the menu bar along the top, select Devices, and select Back Up. This would create a back up under the name of your Phone, keeping it separate from your husbands.