I keep having the issue of accidently attaching another screen session inside of an already attached screen session on my bouncebox at work (which has about 19 screen sessions running..) and because just doing screen -ls and looking for which one is Attached is too much common sense I wrote a little script to tell me, it also has the super handy feature of telling me which session I am in.

It's called amiinscreen (funnily enough), and lives in my $PATH. While not perfect, it does the job so far.

Example:

$ amiinscreen  
You are in screen session: 22704.vds