Hi Amy.
Google doesn't support task sharing, so it would be hard to for me to add that and make it look good. There is a number of things I could do of varying degree of complexity:
The simplest thing would be to make it so that you can email a list of tasks to your husband and he can too email you a list of tasks. In fact this partially works already, see this video: http://www.geetasks.com/forum/t-197525/ I could probably add exporting tasks into email fairly easily.
The next thing I could do is add multiple account support, so that you can add both yours and your husband's account into GeeTasks and see each others tasks. I might narrow it down to one list as well, to safeguard privacy. However this will do nothing for the web site - I don't control Google's Web site so you will be only be able to see/modify you husbands task on the iPhone. This is a bit more involved and will take some time.
Lastly, and I am really dreaming big here, I could create another web site that allows you to see your husbands tasks, and I might even be able to turn it into aa wiget to plug into iGoogle or even into gmail itself. That's will be a lot of work will not happen any time soon.