I picked up The Metamorphica the other week; it's a lengthy collection of (as far as I can tell) totally system agnostic random tables, as well as some notes on how to leverage them. I'd be leery of calling them "random mutation" tables: they cover that, but also insanities, super powers and psionics.
Anyway, the PDF is free, but I ordered the book because I'm a sucker for random tables, books in A5, system agnostic stuff (and it was easy to add to a Lulu order I was going to place anyway).
This thing is great. When I say these tables are all over the place: I'm not kidding. Entries look like this:
I could get into the specific contents (there are 104 body: form entries, 164 body: function entries, etc), but I'm not sure how useful those sorts of metrics are... and it's free, so I'm sure you can figure that stuff out.
At a high level, though: it's mostly mutations/psychoses/powers sorted into groups. Appendix #1 is a bunch of tables for random stuff (plants! colors! animals! body parts!), #2 provides alternate arrangements of mutations & powers, #3 provides instructions for theming those mutations & powers to different settings and #4 provides instructions for creating specific types of creatures (like beastmen, demons, and plants). Again, all of it system agnostic.
Really though, let's do stuff with it.
Here's a mutant: d6 mutations gave me 4.
|780||Lights nearby are brighter and more violet|
So, it's a medium-sized crystalline blob that draws power from the sun, sucking away entire spectrums of light as it refracts through its hideous form. That'll do.
I've got WFRP on the mind, with its myriad and enthusiastic chaos/mutation systems, so I rolled up a few chaos characters. Fortunately, Realms of Chaos is in Metzger's bibliography, so there's a page in Appendix 3 about creating chaos-y characters.
First, a Chaos Sorcerer:
|Gift of Chaos||3||Demonic Weapon|
|Telltale||61||Turns to stone in sunlight|
Nothing mind shattering here, but definitely kinda creepy. I can't find a "demonic weapon" table anywhere, which feels like an omission, but at the same time, even though Slaves to Darkness has something like 18 pages on creating Daemonic Weapons, "has a weapon that's a demon" is kind of enough, you know?
And now, a Chaos Lord:
|Demonic Phenomenon||61||Food and drink spoils|
|Telltale||27||Plants move and try to grab the mutant|
|Gift of Chaos||1||Blood Rage|
|Gift of Chaos||8||Wings|
|Gift of Chaos||7||Pallid Siphon|
The Chaos Lord is more evocative: food spoils in its presence, nature itself attempts to strike at it. It's fickle, and reacts with a violent tantrum when injured. It's got wings and a pallid, colorless siphon, so I guess that makes it a loathsome mothman.
So, this stuff is pretty cool. The doc is great, and Lulu prints high quality books. Definitely check it out. This is one of the neatest supplements I've run into in a while.