java fern can be grown easily, just attach it to an object just make sure you don't bury the rhizome as it wil rot.
Anubias barteri, same rules apply as above
hygrophilia difformis excellent for taking nutrients out water therefore minimizing algae
hygrophilia polysperma, same as above
straight vallis, easy to grow
twisted vallis, same as above
amazon swords, easy to grow, plant in gravel
radicans, slightly harder than above
water lettuce, very easy to grow, floating plant
For a bit of colour - cryptocoryne wendtii red, easy to grow, needs medium levels of light which you have got.
some good plant shops with varieties from, easy to difficult,
[URL="http/www.aquarium-gardening.com/index.php"]http/www.aquarium-gardening.com/index.php[/URL]
[URL="http/www.plantsalive.co.uk/index.php"]http/www.plantsalive.co.uk/index.php[/URL]