I just read this Lee Jones' column in the recent Cardplayer (see below). I don't play in a lot of tournaments, but I think you can see how the kind of situation he describes would be relevant in some cash game situations.
Also, while the story he relates is about extracting maximum value, I think this concept could also be turned on its head when thinking about bluffs and semi-bluffs. I see the all-in bluff/semi-bluff frequently- the idea being that if you make a large bet, especially one that puts all your chips at risk, a tighter player might be more convinced to lay down whatever their marginal, but ahead hand is. I think sometimes a better play is to make a bet that is sizable, but not all-in. I have used this move a number of times (uh-oh - giving away my secrets now) and it really seems to confuse people and make them more likely to fold their marginal but ahead hands more often than simply moving all in. Plus, you can limit your losses in case you get a call. It's one of those situations where the move is advantageous regardless of what your opponents' actions end up being.
Of course, in order for this to work, you also have to use the same kinds of bets sometimes when you have strong hands, so that opponents (especially those that play with you frequently or who have been playing with you long enough for you to have some kind of table image) will actually believe that you likely have them beat.
Copied from Cardplayer:
A Chip, a Chair, and a Plan
A very nice play
"One is the loneliest number that you'll ever do"
If you're one of the producers of the European Poker Tour
television shows, please stop reading now; I'm about to make a pretty
startling confession: Watching a typical no-limit hold'em all-in
confrontation is about as interesting as watching a roulette wheel go
around. For example, it has all the appeal of listening to grass grow.
One of your players gets the reds, the other gets the blacks, and the
guy with the pocket pair (instead of the overcards) gets zero and
double zero (green, for the roulette novices). The point is that once
the cards go on their backs and the dealer starts putting out the flop,
turn, and river, the skill is gone. Now it seems that some
poker commentators think that the "pros" (for example, anybody who's
won a bracelet and/or has announced that he/she is a pro poker player)
have some magical ability to make their 48 percent equity a huge
favorite - or at least, the commentary implies, they deserve to.
But you and I know for sure that if Phil Ivey turns up A-Q against
Hillary Duff's 8-8, we're gonna take Hillary and give the points. That
Phil might be the best poker player in the world and Hillary thinks a
club is where you go after the show has nothing to do with it; Hillary is a 5-4 favorite and all of Phil's talent can't fix that.
This is why I'm much more interested in what goes on behind the scenes
of a poker game or tournament. What happens when there are cards to
come and bets to be made - when we separate the men from the boys; or,
in this case, the women from the girls.
I introduce again my friend Jeanne, whom you may recall from a previous
column. I spelled out in grim detail how Jeanne had played pocket
queens "like a little girl" (her phrase, not mine), and ended up
folding the best hand in a monster pot during a sit-and-go. Well, she's
back, but this time she made what I consider to be a world-class play.
Jeanne was in a tournament at the local casino, and they were down to
five players, but she was in pretty deep trouble. Specifically, she was
down to $2,500 and the blinds were $1,200 and $2,400. That is, she had
the big blind plus one lonely $100 chip. She was on the button and
everyone folded to her. Both blinds had plenty of chips. I won't say
what cards she had - the specific hand isn't important - but suffice it
to say, the hand was "playable."
"I call," she said, carefully leaving her one remaining chip capping her cards.
"Are you all in?" asked the small blind (a co-worker of hers).
"If I were all in, I'd have announced that," she replied.
As soon as she described this play to me on the phone, I sat up straight in my chair; this was incredibly good poker thinking.
Why don't you take a minute and see if you can figure out what Jeanne was up to.
You're back? OK …
"I knew that if I went all in, the small blind would probably call, and
no matter what, the big blind would call instantly. He'd be correct to
call without looking at his cards. Then they'd run out five cards and
I'd have to beat them both, since they'd surely check the whole hand
down.
"But by leaving myself that one chip, I forced them to play poker
against each other. If one of them wanted to get me all in, he'd have
to make a full ($2,400) bet. And he might not want to risk that. And if
one of them did bet, I could fold if I was absolutely sure that I was
beat. Furthermore, if one of them bet, suddenly there would be a
significant side pot; if they really got mixed up in it, I could fold
and hope that one of them busted out."
Now this is what makes poker a fascinating game; I'd rather hear one story like this than 100 runner-runner bad-beat tales.
The story even has a happy ending. As it turned out, the small blind
completed the bet and the big blind checked. Jeanne flopped top two
pair. Both blinds checked - and she checked, too! Absolutely! She still
had the problem of both players getting the right price to call with
virtually any two cards. The turn was a blank, and they both checked
again. And again, Jeanne checked. Finally, when they checked on the
river, she put in her last chip, they both called, and her top two pair
was very, very good. And, in fact, she went on to win the tournament
after making a deal for most of the money when heads up.
But the fairy-tale ending to the tournament is no more important here
than whether the roulette wheel comes up red or black (or green) in my
whimsical analogy above. There's nothing that Jeanne (or Phil Ivey, or
Hillary Duff, or you, or I) can do about the cards that come out. But
by using your logical skills, you can ensure that you get as much of
the roulette wheel as possible on your side. Therein lies the key to
winning poker.
Well done, Jeanne - very nice play.
"Two can be as sad as one" 
that's math/nerd-speak for "pimp" in case you were wondering. As Billy would say: "nerd, nerd, nerd, nerd."
