Blyxa japonica is nice, you can also look for Echinodorus (sp?) tropica or kleiner bar. Java ferns could be considered medium sized too. If you're running something high tech you have a LOT more options.
What's your tank like? Size? lighting?
It's a 20 gallon with inverts. Good lighting (3 14 watt CFL's) and have room for a 4th. I really don't want to have to deal with the whole CO2 thing though.