If the battery is as good as claimed I am hoping to be able to use it for AIM, Yahoo and MSN so I no longer have to remember to click online/offline all the time when I leave the house or lock my PC. Instead I keep the N900 nearby and people can always contact me without the risk of my reply coming hours later.

It should also be a lot easier to quickly look something up and reply to messages while watching TV.

Other than that, making phone calls of course and checking prices when out of the house.

I may still take my iTouch out with me though for the exclusive Apps/Games on that but I am hoping to be able to use my N900 as a MiFi for that, so I get the best of both worlds.

Would be cool if someone wrote a Python app for the N900 that SCPs into the iTouch (jailbroken) and can synchronise the music library between the two devices. Would mean I could buy tracks/videos off iTunes and have them copied over the N900 more easily. I already have copied the file structure over to Linux before and mplayer can play the files fine without any extra decoding necessary.