What is the easiest/best way to make files available off line (offline cache) - I am on Android 2.3 on HTC Desire.. I have an option saying save to phone but all that happens when I select songs and select this button is that the first song in my list seems to download constantly. i.e. finishes and then starts again. But no song is available off line.
I know you use Ubuntu One service, and probably have plenty of your music already there, but I'll give you an alternative solution.
I have the exact same setup; HTC Desire with Android 2.3. For file sync, I use an android program called "rsync backup for Android". With it, you can just select a remote folder on your computer to sync to your phone, through sftp (SSH).
In order to authenticate against your computer, you need to create and use a dropbear SSH private key, wich is very simply illustrated on the program's help.
Hope this helps.