At NA Nature today, i saw Chan growing bunches of this tall, grassy plant in his cube tank (on the right of his large central tank). Superficially it looked like Cryptocoryne tonkinensis, but it clearly has val like side sprouts. According to Chan, it's a type of Vallisneria, though much smaller and thinner in leaf shape than the regular ones. He doesn't have further stock now, but has ordered new stock.

Should be a somewhat good background plant for small (2ft or so) tanks, although some periodic thinning out would be needed (unless one uses acrylic dividers).