1. "Pick a passage of dialogue and increase hostility between the speakers. It can be friendly ribbing, worried questioning, polite disagreement, snide derision, veiled threats, open hostility or any other degree of friction."
Of the three ideas, I think this one is the easiest. When you have two characters who spend any amount of time together, tensions will automatically mount. Little things like misunderstandings, misaligned goals, or hurt feelings can easily produce juicy dialogue. Instead of internalizing the pain, have one character lash out with words. It doesn't have to be negative, either. Good-natured teasing (or an ill-timed tickle-fest) can escalate into tension, especially if there are unspoken resentments or unknown variables (that lovely sense of mystery must be made clear to the reader for this to work, though).
2. "Pick a passage of exposition. List all of your POV character's emotions and find emotions that conflict. Grab what creates unease, uncertainty, fresh worry, new questions, a deeper puzzle or an agonizing dilemma. Rewrite the passage."
This one takes more work, as you've got to establish the conflicting emotions first. For example: in one scene, your female character thinks her husband is planning a surprise party for her. She's feeling a bit excited, but let's be truthful, it's too boring to devote an entire scene to it. Now add an emotion that conflicts. Simple: she hates surprises. Now she wants to find out if he's really planning it, who's involved, where it'll be, how they'll surprise her--and the whole time, she doesn't want her husband to know she's found out. (It's still pretty boring, but if you weave all this conflicting emotion into the main thread of the story, the potential for interest will raise.)
3. "Pick a moment when your protagonist is still, simply waiting or doing nothing. List three setting details that only this character would notice. Detail her emotions. Find those that conflict or surprise her. What's this moment's personal meaning?"
This is the hardest one, especially for me, as I'm not that great at detailing setting. However, it can be done. I'm thinking of J.D. Robb's In Death series. The protagonist, Eve Dallas, is a homicide detective. When she walks into a crime scene, she immediately notes the things that others wouldn't necessarily notice: hiding places, forensic evidence, misplaced items (like moved furniture or pictures askew). Her emotions are almost always under control. But once in awhile, the scene is personal to her--she knew the victim, or feels extra compassion for a survivor, or something about the crime reminds her of an emotionally trying time from her past. That's when the viewing of the scene takes on more meaning. The emotional connection to the setting produces tension.
If you've got a boring passage in your WIP and don't know how to fix it, try using one of these three ideas to increase the tension.
Questions? Comments? Do you have better examples than what I came up with?