Sram powerlink

The best way to clean your bike chain is by taking it off your bike, and dumping it in a bucket with solvent. Gasoline will do fine, but if you don't have garage (like me), storing it might be bothersome. Besides that, gasoline is $2.50 per gallon ($0.66 per liter) now - way too expensive to use as cleaner. I choose to use Simple Green instead.
As good as the theory may sound, there is one problem. Every time you use the chain punch to open and close links, the chain gets weaker since the connection of the pin to the hole is deformed. This is where the powerlink (see picture right) comes in play. Don't think this is a new invention - single speeds and bikes with geared hubs use special closing links for decades (see below)
The old-style links need a screwdriver to be opened; the modern powerlinks can be opened by hand. At least, that is the theory. It takes some practice an supernatural powers to open the link after using it on your chain for the first time. Over time, opening and closing gets easier - I guess a combination of simply getting better at it, getting into the habit of soaking the link in grease before closing it (so it doesn't weld together) and a little bit of wear that makes it -even slightly helps a lot- easier to open it.

The trick is to push the plates together, and then move the two pins of the powerlink towards each other. If the powerlink doesn't cooperate, using pliers helps as well - although using them is not recommended. In case you do decide to use the heretic pliers. but the beaks on opposite corners of the powerlink and squeeze carefully. Another technique is to use some metal wire (hangers from the dry cleaner?) to keep links left and right of the powerlink together, thus removing tension from the chain. Of course, you could also lift the chain of the cogs to remove tension, that's what I do. It's a lot easier!

So, soak the chain. I always start with a couple of baths in plain water to get rid of most of the dirt and grit. Then I switch to Simple Green, until there is no more black gunk coming of the chain. And finally, soak the chain in boiling water. Keep it in the boiling water for a couple of minutes and then lift it out of the water (you still have that clothes hanger around somewhere, don't you?). Since the chain is boiling hot, water will evaporate very quickly and your chain will be dry (even at the inside) in a couple of minutes. Swing it a couple of times around, just to get rid of the last water, put it back on the bike and put the powerlink back (I mentioned before - grease it, so it comes off easier next time). Oil the chain (I recommend Prolink lubricant) and off you go!