I have seen on the nokia website that you can have a maximum of 8 GB in the slot, and 2 GB that come with it. Is there any way to have more than that amount of memory? is there any software that will allow me to have more than 8 GB added on?

As far as I know the only limitation right now is a physical one-

The largest available Mini or Micro SDHC card is 8GB, and the n810 has only a single miniSD slot.

They make 12gb micro sdhc cards, they are just rare and expensive.

The N810 has no trouble reading a 16Gb SDHC card (full size SD) when attached with an appropriate reader with a USB cable/adapter in the micro USB port in OTG host mode. I suspect it will also read a 32Gb SDHC (but currently too expensive to consider IMO) and of course some seperately powered HD's. It will also run some flash drives without external power and maybe even 32Gb or 64Gb versions. (Meritline has a $150ish 32Gb flash drive that MIGHT work but no personal experience).

I am still looking for a single slot SDHC card reader that will be powered by the N810 itself. If anyone has one working I would be very interested to know.

PS: I also expect that if/when MiniSD or MicroSD goes to 16Gb, the N810 will have no trouble reading them.

Check around. This topic has been discussed to death.

Can someone direct me to a compatible miniSD or microSD that is 16GB? (one that can fit into the available port). Thanks

No, I don't think anyone can, because there aren't any (production) yet.

I posted images of my SDHC MicroSD card reader working directly on the N810 somewhere on the forums. Can't remember if it was you who saw them or not - but you do have the option of an extra 8GB MicroSD on the N810 that way! Also happens to be the smallest and one of the cheapest readers on DealExtreme

Any size you can buy, now or in the future (I must have answered this in 10 threads just the last 6 weeks I think)

I've got a 16 GB SDHC card. It works in either 'internal' or 'external' slots. So, though i have 18.25 GB on line (.25 fixed, 16 internal, 2 external), i see no reason not to have 32.25 GB. When prices come down, i might add 32 GB, for 48.25 GB on the n800. The 16 GB card was about $75.