highflyin9, Yesturday I posted a thread similar to this one on a psytrance forum. The only difference between your thread and mine is that I limited my request only to artists that are like Infected Mushroom. I describe being "like" Infected Mushroom as psytrance that's is primarily built around a melody. When I mean built around a melody, I mean that the beat, and all ambient environments reflect and interact the melody and vice versa. You know what EVERY person who replied to my thread said? They said "There's noone like infected mushroom, or even close."
Another quality of my favorite IM tunes is that the melodies are a nice pace. Often in psytrance you've got people calling a series of notes going at 132 bpm a melody. That's not a melody to me. When I think "melody" in regards to psytrance, I think of something I can hum along, or along with at full volume.
Anyway, I still have a little hope. I've been downloading music like crazy and listen to internet radio in search of electronic artists who I could enjoy as much as IM, but so far I've come up with nothing.
In regards to Hallucinogen, The Mysted Muppet (who's newest album is "From the Legend") is a similar artist. They build really dark environments which sound cool, so there's your eerie/ambient, but they don't get my head nodding like IM does.
I wouldn't be surprised if you know about Violet Vision if your an ambient and goa fan, but if you don't, definitely check them out. One of my favorite tracks by VV is "Your Voice", which is a beautifullly written chillout/ambient track. Then again, you may have heard their music already and think it sucks, and that I'm psychotic,