More sci-fi with this theme?

I guess it would be “military sci-fi” along the lines of Starship Troopers or The Man-Kzin Wars. Essentially, stuff with the theme “No, humans aren’t babes in the intergalactic woods. We got where we are on this godforsaken rock by clawing our way to the top, and yeah, you may have advanced biomechanical armor and death rays, but we’re clever little monkeys, and yours isn’t the first toothed, muscled, chitinous species we’ve sent to the Great Beyond. We might be primitive, but we’ve been making war for an awfully long time, and we have at least a puncher’s chance against whatever nasties the universe sees fit to send our way.”

Off the top of my head:

[ul]
[li]The Forever War by Joe Haldeman[/li][li]The Vorkosigan series by Lois McMaster Bujold[/li][li]The Mote in God’s Eye by Niven and Pournelle[/li][li]Footfall by Niven and Pournelle[/li][li]The Legacy of Heorot by Niven, Pournelle, and Barnes[/li][li]heck, pretty much anything by Jerry Pournelle[/li][/ul]

The Halo games and novels fit this theme. Basically the only advantages humans have are their adaptability and the Spartans.

I like Tanya Huff’s Valor series. It’s set in a galaxy populated by dozens of sophisticated, peaceful alien species, but they are under threat from a mysterious coalition of hostile aliens.

So the good guys have formed a space marines outfit that recruits from the three most “warlike” species, one of which is humans. There’s a lot of stuff about how these three humanoid species in particular have learned to live and fight together. The “warlike” species aren’t the most sophisticated in the galaxy, but they are needed and respected for their abilities.

The protagonist is a human female staff sergeant. The books are funny and action-packed, and Huff is probably finished with them after four books. She’s not one to drag a series on forever.

Pournelle - anything
Ringo - The Looking Glass War series, Legacy of the Aldenata series

The game Mass Effect (and its upcoming sequel, and I think there’s a novel) is along the lines of the OP as well. Humans are a bit more of the “newbie” race out in space, but they’re scrappy, and part of the plot of the first game involves trying to prove their merit to the other races out there. You play a military character, too.

The Looking Glass War series is what I thought of.

Mostly what I came in to say. Not only does this list fit your category, but these are all really good reads. A story, any story (not just sci-fi) needs to entertain on some very basic level. Be interesting, be exciting at times, be internally consistent, have good characters …

Go find John Scalzi’s Old Man’s War series. Awesome military Sci-Fi, with just the themes you are talking about.

The *Lensman *Series by Doc Smith has lots of military action, in a two-dimensional, space-opera type style.

Most of the *Retief *stories by Keith Laumer have belligerent aliens which must be subdued, but they tend to focus more on the diplomatic efforts than the military aspects. They’re also funny as all hell.

The Hammer’s Slammers stories by David Drake.

I would say the stargate series fit in this frame, also Stargate Atlantis

Came in to recommend this. Very good read.

See Walter H. Hunt’s The Dark Wing series, in adition to those already listed.

I don’t know whether Eric Frank Russell’s Wasp fits what you’re describing or not, but it’s a good read either way.

Other series out there:

StarFist - Cragg & Sherman

Insurrection, Crusade and On Death Ground - White & Weber

Not so much war-like, but David Brin’s Uplift series has a lot of the “we clawed ourselves to the top!” theme. The premise is that all sentient species had a sponsor - an older sentient species - that basically gengineered / bred a clever animal to true sentience.

Then they run into us Humans… who apparently got there all on our own. This pisses them off. A lot.

Including:

The War World series (collaborative; stories by different authors set in Niven & Pournelle’s CoDominium/Empire of Man universe)

The There Will Be War series (paperback anthologies of military SF, 8 or 9 of them, edited by Pournelle)

The Imperial Stars series (paperback anthologies, 3 volumes, of political/military SF on the theme of empires, edited by Pournelle)
I’m tempted to recommend S.M. Stirling, but his military SF, e.g., The General series (with David Drake), is mostly humans v. humans, in exotic settings; not quite what the OP asked for.

The Old Man’s War and sequels, by John Scalzi, is exactly what the OP asked for.

I came in for this, too - I read the first one and enjoyed it; very Heinlein-y. Are the subsequent books as good as the first?

OOoh - Harry Turtledove’s Worldwar series.
http://www.amazon.com/Worldwar-Series-by-Harry-Turtledove/lm/R2I73OLYMAIT

It’s 1942 (or thereabouts, I can’t remember). World War II is waging hot and heavy.

Then… the aliens show up.

See, they’d sent a probe a thousand or so years earlier, saw that mankind was pretty darned primitive, and figured this would be an easy acquisition for their empire.

Whoopsie!!