I have been fortunate in acquiring and restoring a Tek 4051 recently.
I had used one of these back in '77 to '82 and I still have some
documentation, and I found other manuals on 
bitsavers.org but have not
located any software.   Do you know of any source on-line?   I found
references on this site (Feb. 2009) from other users talking about
building an archive of software for the 4051.
I have keyed in a few short programs to test the vector graphics, but it
would be nice to have the original standard pack tape programs.  Even
printouts would be helpful.   I recall when I last used a 4051 back in
the early '80's we had the ability to dump & load programs using the
serial port, and the ability to un-secret the programs.  If I can find
this information again I would be glad to provide it to help build a
software library for this fantastic system.
Thanks,
C. Archer