The most famous term from Agamben is surely “bare life,” la vita nuda. As often happens, this term actually stems from Benjamin, specifically the “Critique of Violence,” where he briefly mentions blosses Leben. As Carlo Salzani pointed out in our ACLA seminar on Agamben last spring, Agamben’s la vita nuda is not his own translation of blosses Leben, but is instead drawn from the original Italian translation of Benjamin’s work. And as a translation of Benjamin, la vita nuda is imprecise — one would probably prefer something like “mere life” (or, less circumspectly, “pure life”).
Similarly, the standard translation “bare life” initially seems questionable. One might have opted for “naked life” — a translation that is more visceral and more immediately clarifies that this life is emphatically post-political, not (as one might dare to think) pre-. You cannot be “naked” outside the context of social norms, while you can in some sense be “bare.”
Yet there is something ingenious in the translation “bare life” that warrants preserving it beyond simple considerations of continuity and tradition. It somehow straddles the gap between the original Benjaminian term and Agamben’s translation — echoing the way that the term itself is in a weird space of indeterminacy where it is neither fully Benjamin’s nor fully Agamben’s own creation.
An und für sich 
actually, it’s neither. the term comes–in the context in which Benjamin uses it–from Simmel and Rickert’s critique of Simmel. I wrote about the context (and genealogy) of the term in my book The Philosophy of Life and Death: Ludwig Klages and the rise of a Nazi Biopolitics. I apologize about referencing my own book, something I never do, but thought it might be helpful for the discussion here.
Very useful comment on a key term of Agamben’s work, often subject to many confusion (one of the worst, maybe, being the conflation of “bare life” with “zōē”). I didn’t know about Carlo Salzani’s remark.
Although Agamben does not refer to the term often, I find useful to think of “bare life” in relation to Aristotle’s use of ἁπλῶς: that which *is* simply, aside or outside of any given frame of predication (in Agamben maybe, the politic to come as one that takes place beyond the context of law).
I recall a conversation about ten years ago with another translator that speaks to the feeling in your final paragraph. As it went, Agamben settled on “nuda” because Italian lacked a term for “blosse” that had its semantic range. I can’t comment on this because I am not familiar enough with Italian.
Thus back to “bare” and not “naked” in English (blosse –> nuda –> bare) so that the English translation corrected the problem that Agamben had with his own translation. Why “bare” for blosse and not the others (exlcuding “nude” which was considered a poor but necessary choice by the author himself) is an interesting question that would be answered more in Benjamin, since the translator is actually retranslating the term for Agamben.
According to Mario Perniola (if my memory indeed serves me right), one of the sources of the term “vita nuda” is Pirandello’s short story by the same name. It’s available here: http://www.filosofico.net/pirandellonovelle/vitanuda/uno.htm