Well - I have managed to answer my own question

I found a link to PirateBox for n810. This allows the n810 to act as an access point and a web server (with lighttpd).

The instructions are at http://wiki.maemo.org/Maemo_PirateBox

A couple of notes may help you get it working
1. I needed to 'sudo gainroot' to run lighttpd.
2. I changed the IP addresses from 23.23.23.23 to 192.168.1.1 and the min-max to 192.168.1.0-255. I'm not sure if I had to do this, but it didn't seem to work otherwise.

Once you have followed the instructions, running /sbin/ifconfig on the n810 should show an IP address of 192.168.1.1.

Then, you have to disconnect your PC (or whatever - my HTC Desire Z works happily as well) from the standard Access Point to use your new (unsecured) access point.

Check the IP address - it will be of the form 192.168.1.xxx, where xxx was 214 for me.

So the PC is now accessing the n810 as a personal area network. If you have lighttpd setup properly, now you can access web pages from your n810 at http://192.168.1.1/????

Hope this helps
Andy