I'm sure there have been threads like this in the past but as the number of people on this forum has rapidly grown I think it's worth bringing up the topic again.
There are many people I know that don't even carry cash around with them or very little of it, I'm sure you know of some of these people. Now imagine trying to sell them the idea of BTC, where their monetary value is now physically on their computer or a managed site that isn't regulated by the government and has no FDIC insurance. If it is on their computer it can be easily hacked if they don't know how it works or are not tech-savvy. Plus the additions of backups and encryption I'm sure disqualify a large segment of the population from using the software at least until the client is brought up from a 0.3 version to a really robust user interface with automated encryption and backups.
For this reason one of the best things you can do to support Bitcoin is help develop the client for it.
The second thing that I'm sure is paralyzing adoption is the concern for what the banking industry and government is going to do about Bitcoin.