I wish there was an easy way to lock/unlock the automatic re-Orientation. The best way i've found is to add a "Sound & Display settings" widget to the desktop. It would be nice if there was a widget tool specifically for that. Why? Because sometimes i'll be doing stuff with the Nexus while lying in bed, and if i roll over on my side all of the sudden everything goes sideways =P It would be even better if there was an option to lock it in a specific orientation rather than just turning re-orientation off entirely. Although it hasn't come up yet but i can easily imagine being in the same situation but wanting to look at something landscape mode (if i get around to reading the ebooks i've downloaded perhaps?) and the OS insisting that the phone is upright so the text ought to be upright too.
I also wish there was an easy way to see a more accurate measure of the battery amount left than the little graphic. You can get to it via Settings->About Phone->Status, but there's no shortcuts for anything below the Settings level.
If i switch to something else while reading a news article via the "News and Weather" widget, i wish if i jumped back to that app via the hold-home button method that it would go back to the article i was reading rather than back to the news index.
Also, i'd really like a good way to edit and view documents. There are a lot of apps for viewing various kinds of files, but not for editing them. There are various notepad type applications, but none of them seem built to handle large documents. In particular, they don't have the spin-it-really-fast rapid scroll type thing. Google Docs is great for viewing docs i've already created, but it doesn't seem to let me edit them at all. Which is really strange, since coraa managed to find a way around the exact same problem on her iPhone, but i can't do the same on my Nexus One. If i switch out of the "Mobile" Google Docs site to the "Desktop" site it gives me a warning that my browser isn't supported (but the iPhone's is?) and if i click the "don't do this!" link to bypass the warning it still doesn't seem to let me edit anything.