On Saturday, I attended my first Florida Mystery Writers of America meeting, partly because they had a different venue which made it a 2 hour instead of a 3 hour drive, and partly because the speaker, Martha Powers, was going to discuss Suspense.
Although I'm still an avid fan of mystery, making the reader worried about what might happen next is always a worthwhile tool.

I will say I was heartened to hear her opening remarks where she differentiated between mystery and suspense, something I've gone into here several time before. But she also echoed my feeling that the term 'thriller' is being bandied around too freely by publishers as a marketing ploy. A thriller is a suspense, but a suspense is not necessarily a thriller. A thriller should be a suspense on a much larger scale.
Martha Powers doesn't think she writes thrillers. She calls them page-turners.
Her guide to ramping up the suspense:
Keep Reading...
The elements that make for great suspense:
Something major to fear
A memorable character
A time limit (the ticking clock on the bomb – she did bring up the memorable point. Why do the bomb builders put the countdown clocks on the outside?

Methods you can use to crank up the suspense include:
Narrowing the time. If something has to be done soon, it creates more tension than giving the character an extended time period to work with. They'll execute a hostage every ten minutes. They'll release the deadly gas in two hours unless their demands are met.
Let the reader anticipate a crisis. The reader has to know what will happen if the character fails. (As opposed to mystery, where the protagonist is solving the puzzle, but the crisis has already happened.)
Forestall revelation
Appeal to universal fears
Scare, release, and scare. You have to give the reader a chance to breathe, to think things are okay, and then you hit them with another crisis.
Prepare the reader and do the unexpected. Johnny Carson said, "If they buy the premise, they'll buy the bit." So, you have to sell the premise early on. You can't stop to explain a skill set at the height of the action. You have to show the character using those skills (or fears) early on, in a 'normal' setting. Is your character going to have to survive in the wilderness? We need to know he was always going camping as a child. Even in non-suspense, this is an important point. When my hero was stuck with a couple of kids, and he braided their dolls' hair, it was established that he used to show his pony at the fair, and he learned to braid way back then.

As for fears – we know Indiana Jones is afraid of snakes at the very beginning of the movie. So we can fear along with him when he looks into that snake pit later. (And because of that opening scene, we know to expect something with snakes, which adds to the tension.)
Narrow the focus. Make it personal as well as global.
To break the tension (as above, scare, release, scare)
Take time for character development
Use descriptions
Reveal information slowly
Use humorous anecdotes
All of the above need to happen before the climactic ending of the book, where you shouldn't have time to back off. That's not the time to stop and smell the roses.
The end of your book will sell the next one. To that end, it must be:
The strongest scene in the book
Surprising but reasonable (again, the reader has to accept the character has the skill set needed to avert the crisis—Mel Gibson showed in a bar bet he could get out of a strait jacket. Thus, when the bad guys put him in a strait jacket and throw him in the water, we know he has the skills to escape. Otherwise, we're not going to buy how convenient it is for him to be able to do that just when he needs to.)
Over quickly
Worth the worry
Satisfy the reader (which, as with everything else, is subjective, of course)
thanks to Martha Powers for a most informative (and, of course, funny, presentation)