This might be obvious for some of you but it was a nice surprise for me, so I thought I'd share.
I have had the digital T-Rex Octavius for quite a while (octave up and down). Like it a lot, it does really neat clear octaves, tracks really well, and is polyphonic. But as any digital octaver it sounds a bit sterile at times.
So I reckoned I wanted to add an analogue octaver to my board (had been eyeing the Aguilar Octamizer for quite some time), but by chance I ended up with the Moog MiniFooger MF Drive before. And what do you know, this thick creamy OD/distortion combined with the Octavius makes a beatiful thick octaver sound. Brilliant, just brilliant!
So now I got a great digital octaver and a thick synthy distortion, and combined they make a heavy analogue octave sound.