I have used Enterprise Architect to create a simple class diagram. What I can't figure out how to do is make it show the relationships such as 1 to 1, etc...
Seems like a simple thing to show, but this program is not user friendly at all.
It is fairly simple actually - for both Class and Object diagrams you can use "Associate" from the toolbox. Then if you double click the association, you will be able to enter multiplicity under "Source Role" and "Target Role" tabs.