If experience with our own communications is any guide, then the first interstellar message we'll receive from aliens is undoubtedly going to be this:
RE: YOUR COSMIC ASSISTANCE MOST URGENTLY NEEDED.
Hello. I am Young Prince Yirjgun Betel from the Huxdurg-6 system and I wish to interstellar radio with astronomical objects in the Orion Arm in search of an honest and trustworthy life form to partner for most exciting business opportunity this galactic year. I decided to contact Earth because you are a very reputable planet that can assist in a confidential matter of immense benefit for us both.
I want you and I to make a fortune out of a situation that I am obviously left with no better option. The issue I am presenting is that my sun was recently destroyed in a supernova that obliterated most life on my planet, but please do not weep for me: I believe everything happens for a reason. Before my father the Emperor was reduced to cinders he told me of mineral reserves in our solar system he deposited amounting to fifty billion (50.000.000.000) barrels of oil and one hundred thousand (100.000) tons of gold.
Read more of Zachary Martin's excellent piece about interstellar spam over at McSweeney's: http://www.mcsweeneys.net/2011/1/27martin.html - via Nerdcore