First base fungo hits fly balls to center field (helps here if both fungo hitters move up and apart, hitting from about the front of the mound extended towards the bases). Center throws to second, second baseman is cutoff (for us it was, anyways - change to suit your style). Third base fungo hits balls to left field, who throw to third, with a second shortstop as cutoff (but you really don't need one, if you're shorthanded).
This is the drill we ran all through high school. It is the most time effective and skill intensive way to warm up a team, but your boys must be able to play catch! Fungo-ers stand in the "fungoe circles" that any good field has (and if it doesn't, you know where they're supposed to be - just outside of the home-plate dirt circle, towards the dugouts). The catch to this method is this - you have two first basemen, allowing both sides of the infield to throw across. Herein lies the only danger - one of the firstbasemen has a lengthy throw back to a shagger, so caution must be excersized (a catcher with a good head on his shoulders really helps).
This sounds like a lot of information, but with a little practise on the coaches part, it runs quite smoothly. Two to three reps per player in the field per section is quite adequate, and with 14 men on the field, this whole routine should take about 7 minutes. It's quite snappy, and quite impressive. I had many a parent marvel to me after witnessing it - "you look like a professional team!" I wouldn't try the routine with anything less than a 14 yr old select team, but with the talent to do it right, it's fantastic.
Another variation of playing is setting a target (i.e. home plate), and that is the hole for the entire game. For the entire game players go to a different part of the field and try to hit home plate in the fewest strokes.To make the game more interesting players can create certain hazards or obstacles that the players must avoid hitting while making their shot. If a player hits a certain hazard then they may be penalized one stroke, a player can also lose a stroke if he loses their ball while taking a shot.