Floating plants: Amazon Frogbit (very pretty trailing roots), Salvinia Natans (I think that's what it is. It mostly died off as the flow was too strong at the start and kept sinking it), Common duckweed (put in to follow the 'duckweed index method' mentioned on other low-tech threads here. It gets everywhere and is a bit of a nightmare), Giant Duckweed (I forgot the exact variety, got it off eBay. It has red undersides and is mildly less annoying than Common Duckweed). Oh yeah, a little bit of Hornwort.
This tank is currently using very little effort, but I can foresee all sorts of trouble from the soil, large rooted emergent plants, and sunlight. One thing about low-tech (although this kind of counts as high, since I dose Liquid Carbon) is I find I'm more forgiving in my expectations of the plants, which makes the whole thing a more calm process (so far), not to mention not having to faff with CO2 injection. I more or less just set the tank up and left it alone.