I will continue editing the first couple replies I added here as placeholders so this becomes an ever-growing list resources and tips. Have more to suggest, either from the old thread or new info? Reply here!
Summary of the first couple months of last year's thread
There are a lot of bars you can use over on Amazon: http://www.amazon.com/s/field-keywords=pull-up+bar
The ones that don't require screws are pretty stable for dead-hang, but I would be careful jumping up onto it and I wouldn't use them for kipping.
If you're interested in using resistance bands (basically giant rubber bands) for assistance as you train, there are Woody Bands and similar variations: http://www.amazon.com/s/field-keywords=woody+bands
and regarding resistance bands: