Hi Lairewen,
Most of the "low light" plants are fairly hardy, this is because they can maintain fairly slow growth in low light/low nutrient conditions and in many cases don't show much response to increasing levels of light or nutrients. Many of them are fairly dull green.
Plants that fulfil this requirement are Anubias spp., most ferns and mosses, some Cryptocoryne spp., some Echinodorus spp. and a lot of floating or emergent plants, these have access to aerial CO2, and so are not growth limited by dissolved CO2 levels. I just had a look in the shrimp tanks (very limited maintenance, no CO2 and extremely lean NPK), and they both have various mosses, Cryptcoryne wendtii, Potomageton gayii, Microsorum pteropus, emergent Hygrophila corymbosa and a Ceratopteris sp., the larger tank also has an Echinodorus spp., a Nymphaea, Cabomba carolina (we use this in the lab., and it requires higher light than the other mentioned) and some Ceratophyllum.
Both tanks have layer of floaters, Salvinia "auriculata", Pistia, Lemna minor and Limnobium laevigatum. The first and last are indestructible, but the Lemna reacts poorly to lower nutrients, and the Pistia would benefit from higher light and more nutrients. I use the "Lemna index" for fertilisation, if the Lemna is very pale green and visibly declining, I need to add fertiliser.
See what grows from the tanks you already have, and then PM me when you are ready and I'll donate some/all of the above plants to you.
cheers Darrel