What kind of drinks are considered 'Rail Mixers'?

Bars usually have daily specials and one days of the week almost always
has a deal on 'Rail Mixers'.  It is usually all you can drink all
night for $8.00 or after 10:00 they are only $1.00 each.  My question
is: What constitutes a Rail Mixer?  Are there certain ingredients that
are needed or certain types of alcohol?  Also, what are some names for Rail
Mixers?  For example are White Russian, Long Island Iced Tea, or Tom
Collins considered to be rail mixers?

Rail mixer is a term used to refer to drinks made from the speed rail.
 Most bars have two sources for booze:  the full shelf behind the bar
where all the premium liquors are kept, and a speed rail (or more than
one) set close to the ice, the mix and the glasses that can be reached
more quickly by the bartenders.

The liquors on the speed rail are lower-cost brands of the most
popular mixes and usually will have a white and dark rum, a gin, a
vodka and sometimes a whiskey tequila and triple sec too (but the
exact set of liquors on the speed rail will change from bar to bar). 
If you order a tom collins without specifying the type of gin, then
they'll give you the gin off the speed rail (the cheap stuff) and most
bars will consider it a "rail mixer" and all bars will charge you less
then if you ask for a specific gin (if you order a Tom Collins with 10
year old Bombay Sapphire for instance).
As for white russians, most bars will include a coffee liqueur on
their speed rail to make them with but you'll often see a cheap
substitute instead of Kahlua.  If you want to specify the vodka or the
coffee liqueur that they use, then you'll pay more (and you won't be
getting a rail mixer).

As for Long Island Ice Teas, most places will include them on the list
of rail mixers because the Long Island Ice Tea recipe actually comes
from the set of liquors on the speed rail:  most times they'll just
mix vodka, gin, white rum, tequila and triple sec (every clear liquor
on the speed rail) with coca cola and a shot of bar lemon.  It's all
on the rail and so it's usually considered a rail mixer, however some
places charge a premium for it because it's generally made with more
alcohol then other cocktails.

Now you've made me thirsty!

thucydides-ga has it right.  Have worked as a bartender in Las Vegas
where the reference was to "well drinks."  The terms "well" and "speed
rail" are interchangable.  Whichever term is most used depends largely
on what part of the country you are in.

Bottoms up
Digs