Any lexiographical study involving the Greek language possesses a valuable aid in Perseus.
A Dictionary of Sex in the Bible is a lot of fun and well worth looking at. Goshen's Study Bible has a number of search tools for examining biblical themes and passages. One of these tools, Vine's Expository Dictionary, has a listing of the definitions of malakos in the Bible. Boswell's arguments that the Bible does not condemn homosexuality have drawn a great deal of popularity. I have seen them make a number of appearances on newsgroups and on a couple of webpages.