Thanks to the help of Jeinifer Linden and shelah Sunshine, I was able to track down a nasty invisibility bug tonight.
Symptoms:
* You can't see yourself but everyone else can see you.
* Logging out and logging back in doesn't help.
* You always see the "Still downloading your clothing" dialog whenever you log in.
Cause:
* You have one or more invalid body parts
* Creating new body parts using the Inventory context menu (right clicking on a folder and selecting Create->New Shape, New Skin, etc.) has a bug that sometimes results in an invalid body part.
Cure:
1. Go to Edit->Appearance.
2. Go to the Shape tab.
3. If you see a "Create new shape" button, press it. If not, make some change to the shape, e.g., change the description.
4. Press the "Save" button.
5. Go to the Skin tab and repeat steps 3-4. Do the same with the Hair and Eyes tabs.
6. Log out and log back in.
With any luck, this should be fixed in the next release.
Thanks for your patience,
Aaron