Hehe... I own everything Dream Theater... so I'm acquainted with them.
Yeah, Russel is all over the place. Allen-Lande is really fun. Ayreon is probably my favorite band ever. It's a project by Arjen Lucassen. All of the Ayreon albums follow the same story line, and it's pretty nerdy and fantasy (like Symphony X). Each Ayreon album uses different vocalists and instrumentalists from all over the world. Some of them are amazing and completely unheard of. That being said, Russel Allen has only been on the Flight of the Migrator album, but according to him, Ayreon is his favorite band to listen to. Jorn Lande is featured on the new Ayreon album 01011001. Like I said, same story line, different artists. Really cool stuff.
Russel Allen was also on one Star One album, called Space Metal. This is Arjen's other band aside from Ayreon.
I'm just full of info aren't I?