Here are two web sites. The first contains lyrics to nearly 100 union songs. Yes it overlaps with manyalready in the DT, but there are some more recent ones also.

The second site links you to a site called Hard Miles Music - Folk Music and Labor Unions. They also have some CDs available.

http://www.chepd.mq.edu.au/boomerang/unionsong/songs.html#

http://sunsite.unc.edu/hardmile/

rich r