Ha! there are many more...., just to name a few.....Ask her if she can show you how her iphone battery looks like or replaced her iphone herself.

Ask her to show you the slideout keyboard,... don't have??, see if she can customized her desktop the way she want like N900 such as moving around widgets, etc.

Tell her you can expand your storage on your N900... and iphone cannot? .... LOL!!!

Btw, since she is a girl, better don't go too extreme and be gentle