|Old High German English Dictionary||You can add phrases of your own, as well; it's a collaborative effort.|
|English-Old High German Dictionary||A large PDF file with a ton of words.|
|Zedler Lexikon||Something like the Oxford English Dictionary, for German, 300 years ago.|
|Grimm's Dictionary||From about 150 years ago, and pretty easy to use.|
|Etymological Dictionary of the German Language||An old PDF, but has a lot of old information.|
|Early New High German Dictionary||An easy-to-navigate web interface.|
|Middle High German Conceptual Database||A pretty steep learning curve; probably best for only serious research.|
Recommendations coming soon!