The Lexiconc is an easy way to find the Greek and Hebrew terms for words you're interested in. For example, if you run a Lexiconc search for LOVE, the BLB will return a list of Hebrew words (Old Testament) that are sometimes translated as "love" followed by a Greek (New Testament) list of the same.
Theological Dictionary of the New Testament, Vol. 1-10 (REF/BS/2312/.K58) has an Index to English Keywords beginning on page 13. Each word listed links back to one of the other volumes in the set.