There's an art to introducing information into the narrative without being too obvious.
Let me give you a bad example first. In this kind of case, the "info dump" always feels like an intrusion. It's usually a break in POV, and sounds clumsy besides, drawing attention to the impartation of information as if it's coming from outside the story-- reminding the reader that this is a story, that is, Not True. So here is ... bad example, which is actually based on something I read recently:
Sandy was their sister-in-law, as she was married to Tom's brother. She had been educated at Harvard and knew the silver market better than anyone in Providence, the largest city in the state, where she had lived since taking a job with Beckett-Turner, the largest fund manager in Rhode Island.
This sort of "info dump" breaks the continuity of the narrative and takes the viewpoint away from the characters and gives it to... I don't know. Some outsider, the author maybe. But let's say we need to know some of this information. After all, if all we have is, "Sandy walked in, and Tom said, "There you are," well, the reader is going to wonder who Sandy is-- more important, the reader will wonder, "Did I miss something? Was Sandy identified earlier?"
So how to impart this info subtly, without taking the emphasis away from the action and the characters?
First, I'd suggest deciding which of those factoids are necessary. Yes, that she's married to their brother (but if you have that, her being their sister-in-law is redundant). No, that Providence is the largest city in the state. (That is, don't bother to insert little bits that declare, "I did some research!" but have no other relevance to this story.) When you revise, decide what the reader actually needs to know, and note those down.
Then try writing the action of the scene, the dialogue, the introspection, without putting in any of the info bits. That way you'll get the important scene stuff in, and on this, you can hang the info on framework you've established.
Now about the info-hanging. No matter how essential that information is, keep in mind that it is LESS important than the action of the scene. So the way to introduce information subtly is to imbed it in existing sentences. The main clause of the sentence should usually carry the main action in the sentence, whether that is actual action, or dialogue, or character emotion or thought. Other elements-- intro phrases, dependent clauses, relative clauses-- are good places to imbed information, as they are, by definition, subordinate, and the reader will read them that way.
Tom shoved the secret file under his blotter as his sister-in-law Sandy strode into the office.
The reader will register who Sandy is, but know what is most important is that "secret file" revelation.
Now I'm sure you're thinking, "That's not deep POV! Tom knows who Sandy is! So he wouldn't think about her as his sister-in-law!"
Well, POV doesn't have to be deep all the time, or any of the time. Most books are NOT in deep POV, partly because it's more difficult to convey such information when you're confined to the deep perspective of the POV character. In a slightly more distant third-person POV, the reader will have no trouble accepting little bits of explanation like "his sister-in-law". That's just conventional narration, and as long as you keep it short and unobtrusive, the reader will absorb the info and move on.
However, in deep POV, you might need to imbed the information more deeply. So how would you do it? Let's try it:
Tom shoved the secret file under his blotter as Sandy strode into the office. Wouldn't be safe to let his sister-in-law know about the case.
The omission of the subject in the second sentence gives that "deep POV" feel, and separating the "sister-in-law" from the name might make the information seem more like it might have come from his own thoughts. But, as I said, it's especially hard to imbed information in deep POV, because we don't "think aloud" what we already know.
Another way to imbed is in dialogue, but be careful here. The reader is, like all of us, an expert in conversation-- we've all heard it all our life, after all. So we're quick to identify clunky, unrealistic dialogue. My friend Lynn Kerstan warns against what she calls "As you know, Alfonse," dialogue, where characters lecture each other about what they both know. So you wouldn't want this:
"Sandy!" Tom cried. "As my sister-in-law, you know about the family fortune and the difficulties we've had with our hedge fund the last year."
Clunk. So what would work? Think about what he might actually say. What's his motivation here? What is his goal? What's he trying to reveal? What's he trying to conceal? How can we fit that bit of info into what he'd say anyway? Go back to what you wrote of the scene without the info, and think about how you can modify it to add the info.
For example, maybe Tom wants to cozen Sandy to distract her from that secret file.
"Hey!" Tom got up and crossed the room to hug Sandy, blocking her view of his desk and the secret file. He let her go and said heartily, "So how's my favorite sister-in-law?"
The "heartily" is a sign that he's trying, that he's not being completely upfront here. And precisely because of that, the reader might accept a bit of clumsiness, because most of us are a bit clumsy when we're trying to deceive or conceal. It'll sound authentic-- authentically inauthentic. :)
Okay, so what other techniques have you all found to sneak in necessary but obtrusive information?