In light of the Heller ruling today--and because these quotes also are cited in Justice Scalia's opinion--I thought I'd share some of my favorite e-mail signatures.
"One of the ordinary modes, by which tyrants accomplish their purposes without resistance, is, by disarming the people, and making it an offence to keep arms, and by substituting a regular army in the stead of a resort to the militia." ~~Joseph Story
"The prohibition is general. No clause in the constitution could by any rule of construction be conceived to give to congress a power to disarm the people. Such a flagitious attempt could only be made under some general pretence by a state legislature. But if in any blind pursuit of inordinate power, either should attempt it, this amendment may be appealed to as a restraint on both." --William Rawle
"This may be considered as the true palladium of liberty...The right to self-defence is the first law of nature: in most governments it has been the study of rulers to confine the right within the narrowest limits possible. Wherever standing armies are kept up, and the right of the people to keep and bear arms is, under any colour or pretext whatsoever, prohibited, liberty, if not already annihilated, is on the brink of destruction." ~~St. George Tucker
Update: Although I don't use this one as a signature, it really goes to the core of the 2A issue. It is the core of liberty going all the way back to Molon Labe.
“The right to bear arms has always been the distinctive privilege of freemen. Aside from any necessity of self-protection to the person, it represents among all nations power coupled with the exercise of a certain jurisdiction. . . . [I]t was not necessary that the right to bear arms should be granted in the Constitution, for it had always existed.” J. Ordronaux, Constitutional Legislation in the United States 241–242 (1891). (Emphasis added.)