If you've never visited, now is the time to do so. JLE is a wonderful forum for Lutheran theological reflection, and the newest topic, on the Pope's encyclical, Deus Caritas Est, is stellar. I've written on the ethics of food for this journal, and will have a follow-up article in the journal some time in the fall.
Recently in conversation with someone on what it means to be Lutheran and ethical, I stopped together with them at the library to check out Martin Luther's The Freedom of a Christian. Thankfully I see it is also on-line.
p.s. Please note that the on-line version of the essay uses gender exclusive language. It's an older translation. When reading it, just translate as you wish into a greater level of gender inclusivity. The essay as translated in Timothy Lull's compendium of Luther's writings is a fresher translation, if you're looking to read the document out of a book (translator=Jaroslav Pelikan).