Firstly, let me say that Linux Mint has impressed me like no other distribution. I actually run it a fair bit in Virtualbox and live on my hardware, and when a release is made based on Feisty I will probably switch to it full-time. It looks great too!
Now, some suggestions:
1. By default, Gnome doesn't include templates, so if you right-click in Nautilus and go to the "Create Document" submenu, you won't find any pre-existing templates installed! As far as I know, no Gnome distro includes those templates. Linux Mint can easily include some, though - just put some generic blank documents in /etc/skel/.templates/ and they will appear for every user created.
2. On the Live CD, Tomboy's window opens when Gnome starts up. This is probably a bit confusing to new users. How about not starting Tomboy automatically, and just letting the user start it from the Gnome panel applet?
3. MintMenu already has a Beagle search field in it - do you really need a Search button on the Gnome panel too? I'd rather see that little space being used for a workspace switcher.
4. Include the Sound Juicer profile for creating MP3s. The following is the Gstreamer pipeline for that: audio/x-raw-int,rate=44100,channels=2 ! lame name=enc vbr=false bitrate=160 ! id3mux
5. I'd like to get involved in writing more GUI configuration utilities. The catch is that I'm terrible at programming interfaces and just as bad at using Glade - my RAD tool of choice is Pythoncard. If I write some stuff using Pythoncard, and it's good enough for inclusion in Mint, would you include Pythoncard on the CD? I'm sure there are a couple of things you can get rid of from the CD to make way - like gnome-app-install
6. Does anyone specify custom mounting options in MintDisk? I doubt it - anyone who knows enough about what they are doing can just edit the fstab anyway. If you could get rid of those extraneous options, you could include a checkbox for mounting HFS and HFS+ partitions - very handy for Macintel users. I'll send a patch for MintDisk to create the support, I just can't really edit the Glade file and make the checkbox work unfortunately.