Bob McBroom made a limited edition "Slow Burn" pedal, which I picked up awhile back. I THINK he still has some left. Amazing low gain OD sounds and a VERY useable TONE knob with alot of range. Good price too! Well worth checking out while these are still under the radar!
Please do yourself a favor, buy a Lovepedal Eternity. Replace the "Fat" chip with the "Hot" chip. I cannot stress to you how frikkin cool this pedal is. I had to buy a second one cause I love it so much! (only pedal I have 2 of) Does exactly what you describe, with the "Hot" chip will do a real loud boost and the treble boost is so dang musical it's sick... Oh and the OD, smooth and uncompressed. It's a peice of art, man...
Sorry about the goo-goo, love fest, it's all true though.
i'm surprised no one has suggested the bjf honey bee! it IS a low gain od with an excellent tone knob! i JUST got mine, and i am really diggin' it in a big way. it's highly responsive to pick attack. it serves up more bite & gain when you dig in. even a bit of sag! it also has a real talent for blending with other od's. i cn't get enough of it! it's definitely a keeper.
+1 for the Z.VEX Super Hard On. An amazing pedal. Use it in alone or in conjunction with a Klon or other OD/Boost for even more goodness. For a very different tone, it also works well in front of my OCD.
i also agree with the eternity suggestion, even if it is a mid to higher gained od. and that's because it actually sounds great with the drive backed off to low gain. not all od's are good at doing double duty like the eternity is. excellent choice.