If anyone is interested, I use the following programs on my Linux box:
EBView from the repo with dictionaries downloaded from http://classicalepwing.sourceforge.jp/
(Lewis and Short and the Little Lewis)
And the "Felix 34" program which is an interface to scanned images of the Grand Gaffiot. A fully digital version is coming along at the above mentioned site, but they're only at the letter C. Until then, scanned images work nicely.
And let's not forget Whitaker's Words.
EDIT: The best web interface
I've found is http://logeion.uchicago.edu