Simple question, simple solution probably.

I've got a 4gb card that lives in my N810 and is strictly for the N810. Of course my internal memory is filling up because I use the device for more than just internet. I'm just wondering how to extend the memory a little more to either the internal sd card or my removable sd card from the stock 128mb's it lets me choose. I'm pretty good with linux code so terminal commands are fine with me. Thanks,
Chris