For a Bible Handbook/Dictionary, a good one is built into the study tools at net.bible.org so you don’t really have to look much further if you use NetBible as your study Bible. Even if you don’t use NetBible, this is a good link to use for looking up proper names, place names, theological terms, and so on.
It is also good to be aware of Theopedia, or more formally, the Online Encyclopedia of Biblical Christianity: http://www.theopedia.com (This site gets into systematic theology and in some places is extremely Calvinist, but still evangelical). Theopedia is more tightly controlled and strictly edited than Wikipedia, but it is growing in coverage of useful topics.