Hortlund, when you get Res, you want:
SEB NP2 -- available at
http://www.ofp.info (I think), or
http://www.ofp-zone.de[shameless self-promo]Be sure to install the CoC_Mines too. It's in the NP2 zip, but a separate file. AP mines, directional mines, claymores, all those cool things (and full MP functionality without killing your bandwidth).[/shameless self-promo]
Missions are also there.
BAS Delta and Rangers are also supposed to be good.
the avonlady's faq has a lot of useful links to just about everything you'd want.
Also, the official forum has some good announcements.
If you're into editing,
http://www.ofpec.com has no peer.
If you get way too much into scripting, and want to do something sick with OFP, check out what we're up to over at
http://www.thechainocommand.net . It takes OFP and gives you command over anywhere between a platoon and a battalion. We're currently developing the MP version.