I've also got java fern growing like gangbusters in my low brackish tank. Also water sprite (although at higher salinities I have noticed it tends to drop leaves). Anacharis and hornwort also do great in some salt.
the thread linked by loaches r cool said that anacharis tends to melt in salty water, but I haven't noticed that until salinity gets pretty high, like near full marine (mishap in a small molly tank, the molly was fine, the anacharis was not, salinity was near 30 ppt).
From what I have read it works for some and not for others. I tried anacharis in my first brackish plant attempt at around 1.006ish and the stuff disentegrated in under a month. I cant remember how long I acclimated them though - perhaps it was too short, I just cant remember.
I had good luck with jungle val too. I noticed with val that the original plant didn't do well but the runners were a lot better. I also tried anubias and wisteria. These were a failure for me. I had high hopes for the wisteria. My water is at 1.004.