"Boku Wa Motto PIONEER (I'm a Pioneer)"
"Tsuki No Tragedy (The Lonely Moon/Tragedy of the Moon)"
"Washu's Heartache"
"Washu No Komori Uta (Washu's Lullaby)"
The unnamed BGM from Tenchi Muyo! Ryo-Oh-Ki #9
The instrumental version of Ryo-Oh-Ki's Dance
                       and
The Mystery J-pop (From one of those Tenchi compilation CD's)
Were arranged by  Mike Bromery .

The theme to "The Tenchi Muyo Universe"(a.k.a. Tenchi TV)
                      and
The theme to "Shin Tenchi Muyo" (The second TV series)
Were arranged by  Kevin Shiue .

As for the rest:

"Tenchi Muyo! Theme of Ryo-Oh-Ki" (intro to the 1st OVA)
"Mahou Shojo Pretty Samy (Magical Girl Pretty Sammy)"
The remix of "Mahou Shojo..."
The theme to "Tenchi The Movie:  Tenchi Muyo In Love"
The theme to "Tenchi The Movie 2: Midsummer's Night Eve"
The closing theme to "Shin Tenchi Muyo"
"Aeka Bojo"
The theme to "Pretty Samy TV"
 "Chooshininotteorimashita", The 2nd end theme for "Pretty Samy TV"
"Pretty Coquetique Bomber", The song Samy sang in her TV series(#5)
The BGM from "Pretty Samy TV"
"Kagato's Organ"
The other unnamed BGM's from the OVAs

We don't know who arranged them.  If you know, please e-mail  Preist Techie or  The High Priestess, a.k.a. Cuddly Battleship Kattywampus .

SPECIAL THANKS GOES TO "GenSao" OWNER OF  GenSao's Tenchi Muyo Homepage