2nd EDIT: I just noticed there was a separate forum for this. Sorry about that. Please move it at your earliest opportunity.
For those that are still struggling to create a list of songs to play for people that they can sing along with I offer the following:
Ob-La-Di, Ob-La-Da by the Beatles.
Holy cow this song is super easy and VERY distinctive. People will recognise it the second you strum the first chord. And the best part is it consists of A E E7 D and F#m7 (which is the only real challenge in the song). You can add an A7 and an Asus2 but can really cheat a good version without it.
The thing that makes this song so distinctive: CAPO on the 1st Fret. You gotta go out and buy one but trust me, you will think your last name is McCartney after putting it on.
Edit - I tried to enter the tab here but is just got mashed so here is a link to it:
http://www.911tabs.com/link/?1193881
Cool huh.
Enjoy