Any advice on wiping my private info for reselling the tablet?

Thanks

1. Reflash the latest firmware.
2. Reformat the memory card(s).
3. Reset the lock code to "12345".

This should be part of the Wiki or a faq somewhere, if it isn't.

Agreed. If it's not in the wiki yet, I'll add it later today.

And a good thing to remember to do!. I bought my n810 second hand on e-bay. and was surprised to find when I booted it that it still had the old owners setup I could access their google mail, facebook, IM as well as some other sites that they had saved login credentials for. the works!
Lucky for them that I'm a nice guy and deleted all that stuff, I also sent them a note suggesting they be more careful in the future.

there's no Derek's boot-n-nuke equivalent for the tablets, if that's what you're wondering. and there's no need. wiping out flash memory (reflashing internal memory and reformatting SD cards) leaves no trace of old data like it does with hard disk drives, so you don't have to do anything special, really, to ensure that your private data is completely and permanently erased from the device. do what sjgadsby says. no worries.

Not true. There's not much risk of someone pulling old data out of the internal storage of a reflashed tablet, but SD cards and the internal MoviNAND storage on the N810 are a different matter.

Just as with hard disk drives, etc., until the old data is overwritten, it is recoverable. Recovering photos is especially easy due to the wealth of software designed to save family vacations from accidental deletion. See the Google search results for "flash card data recovery".