"Drinks or info chummer, both cost. One costs cred and the other costs favors. Too much of the former will give you a killer hangover, and too much of the latter might just kill you altogether."
A bartender contact/info broker for the Shadowrun rpg setting, can be easily adapted to any cyberpunk or other high tech campaign.
You come upon a ruined building in the back section of a city park (or other out of the way area of the city). The ruins are fairly overgrown. All that is really standing is a doorway and its frame. If you pass through the opened door, you travel to a different world. If the door closes, there may not be a doorway back to get you back.