I would like to use RP to create a portable Unix device, something like Nintendo DS. Has anybody have information about the monitor and the power I need to use to make RP as a portable device?
For monitor/screen information please read this : http://elinux.org/RPi_Screens You can find information which screen devices are supported. For example this guy uses 1.8" TFT LCD screen. http://www.whence.com/rpi/
For power supply i suggest USB portable batteries (power bank). I'm using Yoobao YB642 11300 mAh battery with my Rpi. http://www.yoobao.com/en/product.asp?b_id=143&a_id=295
In terms of the screen depending on your need you could have the pi connect to a phones local wifi hotspot and then shh into it with that phone (this works lovely on my iphone i am sure other platforms will have simialr apps)
+1 to using the usb portable batteries. you can get some pretty serious ones now that look similar to an external HDD in terms of size and weight that will power it for hours (probably outlast your phones battery life if that is the method of control you choose)
Your goal is similar to a project of building laptop with RPi so you can learn from it.