How to manually set the N800 with OS2008 to host mode.
For use with typical or non-OTG connections. For example the USB cable that ships with the N800 combined with a Female A to A gender Bender.

1. Download becomeroot
http://eko.one.pl/maemo/dists/mistra....1-2_armel.deb
2. Open Xterm and type:
2.a. sudo gainroot
2.b. echo host> /sys/devices/platform/musb_hdrc/mode
-You will see a 'USB device not Supported' message, then it will work.
-Inserting a USB drive opened File Manager to the new drive.
-Insufficient power will cause some keyboards/mice to perform erratically.
3. To set N800 back to OTG mode, do:
3.a. echo otg > /sys/devices/platform/musb_hdrc/mode

Hint: Copy/Paste /sys/devices/platform/musb_hdrc/mode or Just use tab-completion. Type /sys/de <tab>/pla <tab>/mu <tab> and it will autocomplete the command line for you. (yoinked from below, thanks)
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I am about to add the above to Wiki. Any Comments? I dropped the 'if otg mode doesn't take' since I tested it on mine and it went back to otg mode without problem.
**Ponders**
How to flash N800 using N800 instructions? (just joking)
Will the N800 charge via USB in host mode? Would that allow you overcharge the battery causing the famous Nokia Battery explosion? I tried it momentarily and the battery icon does not indicate charging.
I will test a mouse ported through a powered USB hub in a few hours.