Please let me know thank you,

There's a list of them here: http://planetfallout.gamespy.com/wiki/Fallout_3_Easter_Eggs

They're just hiding in plain sight and there's alot of them, that's why not all may be actually considered Easter Eggs.

in my van

Do we consider pop culture references to be easter eggs? At least of a sort? I kind of do.

Anyway, CJ Young over in Rivet City will sometimes say to the lone wanderer "Howdy Mistuh", in a rather Walter Brennan-like voice that makes me think that some old western movie from the 40's or 50's is being referenced or given a subtle shout-out to. But I can't quite put my finger on which one, or even if it's such a reference, or if I'm just imagining things.

You mean like the Lincoln shrine in Arlington?

how the pole in Big Town (i Think) that says Tes-04, a reference to Oblivion

Bittercup -- reference to Morrowind.

in one of the satilite arrays if you blow up a borded up door a giant teddy bear will appear.

http://i.imgur.com/4NdtEpd.jpg