Wheels...std widths?
 

I'm curious about wheel sizing. Are there standard widths for different type wheels such as hybrid, road, mountain? Thanks

Not really.
I've got a couple low end wheels marked 26x1.50 & 26x1.75. The 1.50 is wider!
I think for a lot of low end bikes, it's the lowest bidder with a wheel that will "work".

not standards by any means but common sizes for,

road: 700x23 or 25
hybrid: 700x32 or 35 or 38
mtb: 26x 1.95 to 2.2

There is a table at the bottom of this webpage that shows the range of tire sizes that will fit on a given width rim. http://www.sheldonbrown.com/tire-sizing.html It is generally 1.5 - 2.5 times the internal width between walls.

Well, there's the rim width which can run from 13mm to 25mm (inner rim width). See Sheldon's article on tire sizing,

and there's the rear dropout spacing. Newer road bikes with 10 speed cassettes typically have 130mm spacing while mountain bikes typically have wider 135mm spacing. See Sheldon's article on frame spacing.

I was asking about the inner rim width. When I look at wheel sets on different on-line stores, I don't see any reference to that so I was wondering if that meant there were standards used for current wheels.

There's variation between brands of rims, models, etc. Harris Cyclery carries a lot of different rims, and one of the things they list for at least some of the rims is the inner width. Check the various rims out here:
http://sheldonbrown.com/harris/rims.html

^^^ My mistake, apparently most of the widths listed on the Harris site are outer widths. But still, it gives you an idea of the variation there is.