IC Package resource

[Jiggy-Ninja]

Is there some place online where I can find physical specs (dimensions, pitch, etc) for various IC packages, especially all the jillions of SMT varieties, so I can easily compare them?

I'm doing some shopping on Mouser/Digikey, and I don't have any easy way of knowing what the differences are between things like SOT-108, SOT-337, and SOT-402 (which all look the same in the pictures), or if there even are any significant differences.

[MATLABdude]

That's quite annoying, no? You should be able to flip through to the end of the datasheet for package dimensions (CAD drawing of the IC along with the dimensions). Sometimes, you can even see suggested footprints (those these are really quite rare).

The following page (and some of the ones linked to on the left-hand column) may be of benefit. Keep in mind, different manufacturers often have a nasty habit of not always following each-others specs, so always verify footprints against specific datasheets.
http://www.ti.com/sc/docs/package/guide.htm

The obligatory Wikipedia / Wikia pages that may be of some benefit:
http://en.wikipedia.org/wiki/Chip_carrier
http://en.wikipedia.org/wiki/Integrated_circuit_packaging
http://en.wikipedia.org/wiki/List_of_chip_carriers
http://how-to.wikia.com/wiki/Howto_identify_chip_packages