I want to know if it is possible to "save Passwords" with my new Treo 600?

When I go to a website (secure) that asks me for a user name and password.

the password box says "unassigned" and has a pop-up to change to "assigned" . Is there any way (perhaps with aftermarket software) to
permanantly "save" the user name and password in the Treo 600, Please?