Guide to physical dimensions of SMD components?

[planetscape]

Is there a comprehensive guide somewhere to the physical (x, y, z) dimensions of SMD components?

I'm going nuts trying to figure out the sizes of "SMA", "SMA-sub", "SMB", etc. parts and how they compare to 1206/0805/0603 resistors/caps, and so on.

I'm going crazy trying to figure out what I need to order in terms of diodes (1N4007, say) that will work with a board designed for a 8-pin SOIC chip, for example.

Help!

Thanks in advance!