Using the OTG, couldn't you rewire the power to use, say, a 9v battery? That way, you could use a wifi adapter
you'd probably be stuck with a text based browser, though. Not even the nspire has enough ram for many pictures, even if its ram was empty.
Yes, you can wire up a 9V battery to the port and supply power to devices that way instead.
http://brandonw.net/calculators/ has instructions on how to build such a cable.
The Bluetooth driver still has a long way to go, but there's enough to initiate communication between two calculators and transfer raw data back and forth.
The wifi driver is much further behind and requires specific devices -- the one I'd like to support most is the Nintendo DS Wi-Fi USB connector, as it supports functioning as an access point and has open-source Linux drivers we can study.