Okay, so I'm currently running a campaign (based on Paizo's Shackled City adventure path) and playing in another (homebrew by my buddy Steve). The set of people involved almost totally overlaps, eight in one game and nine in the other. The problem is that aligning the schedules of 8-9 adults with full lives is like getting the planets to align. So, unfortunately, each game only runs every 2-4 months. That is just not enough gaming! So, my buddy Kaiser has started a bi-weekly Wednesday game with a couple of us us from the main group (hi, Kirk and Bill!), another gamer from the area (hi Mike!), and another gamer totally new to tabletop style RPGs (hello Keeton!). We resolved that this group will not be another attempt at a full-scale campaign. Rather we will aim for convention style scenarios, playtests of various games and rule sets, and other one-off events. If some of the short scenarios feature the same characters and loosely relate then that's fine, so long as it's understood that we're not attempting a full-blown campaign.
Our first session was a game of Old School Hack (OSH) which I ran for Kaiser, Mike, Keeton, and Bill. When I first came across OSH I was immediately taken by the simple, fun design and the creative manner in which it blended elements from early D&D and 4th Edition. So, I was quite keen to try it out in actual play. However, I decided that for these "off-night" games I would deliberately avoid doing any deep prep. I had recently discovered the excellent blog Dyson's Dodecahedron (http://rpgcharacters.wordpress.com/) and it's many excellent maps drawn in an engaging style. I grabbed the "Oathbreaker's Hall" (http://rpgcharacters.wordpress.com/2012/04/13/friday-map-oathbreakers-hall/) map to use as a dungeon. For the larger world setting I grabbed the excellent "Map of Nevermore" by SozokuReed posted at www.deviantart.com. For the starting castle-town I grabbed the flavorful "dungeons_and_dragons_map" by firstedition, also from DeviantArt.com. I grabbed some monsters from the game, made up an orc shaman, and invented several mind-bending traps. In town, the local priest character provided the PCs with the plot hook to travel to the dungeon and also a lore-poem (which contained clues to the four main traps).
The game went very well, with all the players fully getting into the spirit of OSH and the don't-take-it-seriously attitude of a one-off game. The newbie, Keeton, easily got right into the full spirit of roleplay at the table. One thing which was a major takeaway for me was that I was suddenly able to grokk what people have been saying about the roll-playing of skill vs. old school style role-playing skills. OSH dispenses with skill rules. Instead you use attribute rolls (six attributes, but very different than those of D&D) supplemented by the player's noggin. It really brought out more creativity in approaching various challenges than the D&D 3E/4E style skills usually do. Thus I was not only entertained, but enlightened as well.