Some of these you may or may not already know, and I'm not going to include all the vocaloids, but hope you enjoy reading this anyway. I might add more to this as time goes on, but don't hold me to it >.>
Hatsune Miku: The first sound from the future
Kagami : Mirror (Mirror image, Rin and Len can be considered mirror images of each other, as said by the company)
Rin: R for Right (like on Headphones)
Len: L for Left
Mergurine Luka: Sound that goes around (because she sings in both English and Japanese)
Prima: from the term "Prima Donna"
Sonika: Hindu name for "Golden" (she wears a yellow coat, idk bout this one not to confident in it)
Galaco: original doll designed by a group called galaxxxy, dress has a space (Galaxy) design on it, Galaxy=Galaco
IA Aria On the Planetes: While IA is taken from her provider Lia, Aria On the Planetes, Aria can mean either open space(Latin) or air(Italian), Planetes means planet (Greek)
Kaai Yuki: ai=love uki=song
Hiyama Kiyoteru: Hiyama is from his provider and is a play on words to also mean ice mountain, part of his profile is that he plays in a band named Ice mountain.
Gachapoid: his name is derived from Gachapin, the character's he's supposed to be like.
Aoki Lapis: Aoki means Blue Princess, her full name and color scheme are based on the Lapis Lazuli gem.
Kokone: Heart sound
Vocaloids who's names are based on their voice providers names: YOHIOloid, Gackupo, Gumi, Piko, Miriam, and Meiko. (maybe some more...?)
UTAUs, fanloids, derivatives etc. just a few
Teto Kasane: Kasane- double or piled up sound. Teto- short for Tetopettenson
Akita Neru: Akita-get bored, Neru- go to bed (got bored, went to bed)
Momo Momone Momo-Peach, Momone- peach sound
Uta Utane (Defoko): Utane- singing, Uta- Song, Defoko- Default child.
Haku Yowane Yowane- negative thoughts Haku- utter, (to say negative thoughts)