Build you own combo dock for iPhone and iPad? You will be able to get the DIY guide at Geek-Gadgets on how to combine both of the device. If you have a bit of spare time and DIY hobby, this is an interesting task to peep into.
At least, this DIY gadget show us how geeks those folks at Geeky Gadgets. Browsing internet on your iPad while replying tweets with your iPhone? 😉