Is there a skill or ability that allows someone with some kind of leadership ability or tactical know-how to provide a bonus, teamwork or otherwise, to the group? I'm looking for a character ability, not Battletac. I was thinking they might have something like that in War!, which I don't own (yet.)

The Leadership Skill fulfills that function.
There is also Small Unit Tactics (A Knowledge Skill) as well.

Yep, even that book had its merits

Leadership, as I read the skill, is used to get someone to do something. It works like Intimidation, but is used under different circumstances. Am I missing something?

How is Small Unit Tactics used?

War!, page 137... You need subordinates for these skill applications to work. For an unwilling opponent, it only takes an Opposed Leadership (Persuasion spec) + Cha Test. Each of the following require a Complex Action to complete.

Command (Strategy spec): Leadership + Logic Test, threshold of half your subordinates (round up). Results in +2 Initiative for the next CT.

Direct Fire (Tactics spec): Choose a target. On a successful Leadership + Intuition Test (same threshold as above) all subordinates get +1 dicepool on attacks against that target for the rest of the CT.

Inspire (Morale spec): Leadership + Cha Test (it doesn't seem to list a threshold, I assume it's the same as above). Effects are different if you're Inspiring PCs or NPCs. NPCs act as 2 Profession Ratings higher until the end of combat. PCs get +2 dice for Composure Tests for the same duration.

Rally the Troops (Gut Check spec): Leadership + Cha (2) Test. Success allows subordinates who have failed a Morale or Composure Test to make a new check.

Special note: using a TacNet (regardless of TacNet rating) applies an extra +1 dicepool to all of those effects.

Dammit, more stuff in books I don't own...

I posted the gist of it. It honestly wasn't that good, in my opinion. It's more something that mooks would use to slightly inflate their dicepools against players.

Yeah, I get that. It seems pretty tame/useless, honestly. Given the option of having a Leader character or another Street Sam, I'd take the Sammie. It would've been a cool niche for a Face, though, to double as a Tactician.

I don't know. People invest a whole lot to get +2 to their initiative score. Having a guy who can do that for the whole team for the cost of free (Leadership being the 4th skill in the influence skill group makes it basically free) is pretty awesome IMHO.

So a quarter of the application of that skill makes it vaguely worthwhile. Thanks for clearing that up.

I don't recommend spending points on it. But if you're buying the Influence group, you have it. So use it.
If initiative is close, your face blowing a turn so the rest of your team can go first is a good choice to have. +2 to initiative is pretty expensive to get in other ways. Sorry, +3, because every one runs tac-net. Or +2 on all of their attack rolls. Or re-rolling a failed composure test. These things aren't awesome by themselves, but they can make a face, who is often a sub-optimal combat character, useful in a fight.

As I'm a generous GM, I'll also include the critter Fear power in the "composure" test category, because that really seems like what it should have been any way.