Your Indispensable WWII Game

[Silent Disapproval Robot]

Silent Hunter IV with the Trigger Maru mod.

Iron Front: 1944 but only for online co-op.  The single player experience is poor.

IL-2:1946 for online PvP although it's pretty long in the tooth now.

[Bison]

Man I forgot about Silent Hunter 5.  I loves it too.

[sandman2575]

By 'modern' I mean after ~2000. Company of Heroes, eh? Nice. I have the anthology here. Operation Star I have been lusting after for a long time. Is there a gold package for it?

A gold version for Op. Star sure would be nice, but I wouldn't hold my breath.  For as great as the game is (and for my money it's the best platoon/company level tac. ww2 game out there -- ahead of Combat Mission and miles ahead of Theatre of War), it's a pain in the ass to install, patch, and update w/ the add-ons.  Graviteam seems uninterested in improving this -- or in making the game moddable (the serious lack of mod content is another strike, and not a negligible one imo).

[jomni]

World of tanks. LOL!

Disclaimer: I disposed of it a long time ago.

I don't have the Combat Mission x2 engine ww2 titles but my vote goes that way.

[Sir Slash]

CMFI- Combat Mission Fortress Indispensible. Along with CMBN when I'm in a Hedgerow Hunting mood. Silent Hunter's damned good but not --indispensible.

[Greybriar]

By 'modern' I mean after ~2000....

I suggest:

Strategic Command: European Theater (2002) - It's an updated Clash of Steel: World War II, Europe 1939-45 (1993).

Company of Heroes (2006)

Panzer Corps (2011) - As you probably know it is a remake of Panzer General (1994).

Then there's Hearts of Iron III (2009) and--as others have mentioned--World of Tanks (2011) which you might like.

[Bison]

I forgot about Conflict of Heroes...

You are forgiven.  Although I do remember it garnering some awards from some wargaming site on the intrawebs....now if I could only remember the site....

[MetalDog]

Hearts of Iron II Doomsday.

[Yskonyn]

Hidden and Dangerous (both were great)

Commandos

Combat MIssion series

[Nefaro]

By 'modern' I mean after ~2000. Company of Heroes, eh? Nice. I have the anthology here. Operation Star I have been lusting after for a long time. Is there a gold package for it?

That was on sale at Gamersgate, all last week.   For like $7.50.

[spelk]

Decisive Campaigns. Both.
Command Ops: Battles from the Bulge.
Maybe all of Joni Nuutinen's games and Small General: Eastern Front (basically a mini-version of Decisive Campaigns) on the Android.

[Father Ted]

Iron Front: 1944 but only for online co-op.  The single player experience is poor.

If we're talking online FPS, then Darkest Hour

IL-2:1946 for online PvP although it's pretty long in the tooth now.

I like the lateral thinking here!  And I must heartily concur.

Otherwise Combat Mission (CMx1 and CMx2) and Command Ops

[Shelldrake]

For me it is Company of Heroes with the latest Blitzkrieg mod and map pack. Wicked AI and outstanding graphics along with a greatly enhanced tech tree. I often play this co-op against the AI with 2 or 3 friends. COH may be long in the tooth but IMO it has yet to be surpassed.

[Zulu1966]

Definitely, Definitely the Combat Mission Games.

[jjdenver]

There are a lot of those.

Commander Europe at War with GS 2.1 mod
All of the SSG WW2 titles
HPS PzC titles
and I'm not sure it's indispensable but I always enjoy Hearts of Iron 2. I still need to find a mod with a good AI that can invade europe as allies and handle the pacific war well.