Nexus One's internal memory is quite insufficient.

I've occurred problems related to insufficient internal memory after over a month of using the phone. I came from an iPhone, so I never look how many applications I have, as soon as they are "fitting" me. I've been able to install many applications, because they are specially designed to occupy as less as possible, because it is known that Android 2.1 (and previous versions) doesn't support installing applications on external SD cards. First time when my Nexus informed me that it was running "low on space", happened just a few days before media got the 2.2 update (which I also got, manually).

In case you didn't know, Android 2.2 allows installing applications to SD cards (or more exactly, moving them after installation on SD cards). But this is just a theory, as there are applications which doesn't allow moving themselves to the SD card. Actually, there are only a few applications which have this possibility. I mean, I have about 90 applications and I was able to move only 2 of them on the SD card.

The Nexus has 196 MB internal storage memory, and I have free only 13 of them. I know that I have a game which occupies pretty much of that memory (about 25 MB), but because I like it I don't want to delete it (and I can't move it to SD card). Of course, if I need more storage for the phone, I will remove it (and other applications if needed).

Google didn't bring something which helps much here (with 2.2 update). I think that they must now make pressure on developers, to design and update their applications with supportability for SD cards.

Android 2.2 Froyo stops supporting .aac files for the media player.

This is something I discovered yesterday, when I was heading towards somebody. When I tried to play my playlist (all songs were downloaded directly on my Nexus with a third-party application, from YouTube, in .aac format) I was notified that this format was not supported (anymore) by the music player.

OK..so I downloaded the songs on a computer in .mp3 from YouTube (because I was in a rush) and sent them to my phone. Then, when I was going home, another surprise. Even if the downloads from YouTube are not done in a very high quality, the .aac songs were more that OK. But the mp3-s were worse than anything else. I had difficulties in even understanding what the singers were saying. So, Google screwed it up a little.

What you have to do is to download the music externally (not from YouTube, because they are mainly in a low quality), preferable is directly in .mp3 (because converting can affect the quality!) and then to send them to your phone. You can send them via your USB cable, but as I observed that the media player "feels" the changes with a considerable delay, I recommend you rebooting the phone. If it still does not see your music and you are sure it is in .mp3, play a little with the player and then it should update the list with the new songs.