I had been experiencing the "Apache Tomcat; HTTP Server 500; Internal Server Error" for quite sometime.
Recently I found that if you are getting this error message when you are logged into blogger.com, simply sign out and sign in again.
And remember to refresh all the blogs you are reading!
I also found some goodies in the How To (for every blogger) section and Blogger Hacks (for those who know html and xml only) section in the Blogger Help. Check em out. It's worth, really!
By the way, The Green Room is hip n happening!