Lifehacker featured a nifty online tool - BibMe - which lets you add sources, auto-creates entries in various formats (APA, MLA, Chicago), and enables you to save and export your entries.
I registered for an account, which says you can store up to 20 entries. I suppose they will eventually charge if you want to store more. Also, the website refused to acknowledge that I was logged in.
In any case, it's good particularly for the more esoteric sources. No need to refer to that style manual. Just choose the source on the tabs, search for it, then copy and paste the entry.