A while back, I got some of the Vallejo Sticky Textures, and while there are quite a few different selections, I purchased the ones with the greatest contrast:
These are like a wet paste, very granular in nature, that are extremely adhesive. I was not feeling like doing the usual basing procedure for a dwarf that I am painting for my friend's Mordheim band (Hi, Mat!), so I thought I'd put some of this on. I'd generally never take a mini this close up (it's an unrealistic size), but I wanted everyone to get the idea of the texture, which, conversely, is hard-to-gauge if you're not close-up on it.
One of the best uses for these are weathering; you can add pigments to them, add paint to them, etc., so that if you wanted to put some dried, stuck-on mud on a vehicle, this would be an easy go-to, and you could augment the color and consistency by adding different pigments, maybe a brownish red paint, matte medium, etc., to the mix.
The Black Lava one is a lot like a airplane tarmac or black-top; it reminds me of an outdoor blacktop basketball court. These are perfect for sci-fi city-scapes, and I plan on using these a lot with my newly-arrived Sedition Wars minis.
Hope this is something you might find interesting and check out.