Well... technically it's a smaller problem if you look hard enough. While yes the "not invented/built here" syndrome exists, I hardly think that it's good for the military. While foreign equipment is not as widespread use, here's a few examples of foreign equipment (least in the US Army anyways):
120mm Smoothbore M1A1/2 Main Gun = Rhein Metall: Basically there was nothing better on the market, and as the name suggests, license produced from ze Germans.
Some British Engineer Vehicle = Alvis comes to mind for some reason, but is AFAIK a British design that is used in the Engineer Battalions, if my info is correct.
Fox (Fuchs) Chemical Recon Vehicle, yet another vehicle from ze Germans
AT-4 shoulder fired AT Rocket = Bofors Sweden, you can even find the FFV serial number if you know where to look
XM320: Heckler & Koch design, replacing the M203 eventually.
M240B/M249 Machine Guns: Fabrique Nationale, produced here in the good ol' US of A. Belgian design.
M416: Heckler & Koch, basically a more reliable version of the M4, finding use among CAG (Combined Action Group, formally known as Delta Force).
Thales, a French communications company, we use the MBITR
Joint Strike Fighter: While yes, this is a multinational project, it's apparent that even US aerospace engineers need some Euro help, particularly of course since those European nations are wanting the JSF.
AGM-142 Popeye... Not sure but is of Israel design or least produced for the Israelis, I'm not actually sure as my own info is really sketchy.
Durandul: The wonderful retarded anti-runway bomb, French design.
K-36 was tested for JSF, Russian ejection seat.
Kh-31 missile shell considered for CIWS system development against supersonic targets, Russian design
There's plenty more hanging 'round but that should be a good start.