I ran across this application today, called CommitteeCaller.com, which makes it easier for (U.S.) folks to contact their representatives. It's a nifty example of the type of applications that become possible when some imagination gets combined with lowered barriers to entry. This is what mashups are all about. Taking information that is out there on the Internet and combining it in ways that make it more useful, accessible, relevant, visible, etc.
This particular one uses Asterisk for the telephony, a database built from information on the Internet, and a custom AGI to interact with the user input, look up things in the database, make the calls, and get post-call rating feedback. AGIs are the equivalent of HTTP world CGIs (yes, the Asterisk world is progressing quite fast but the Web did get a big head start on it so it's still a little behind; CGIs, or AGIs, are pretty 1997 but you have to start somewhere).
Just wait until all the old school web developers that are used to coding in PHP, Ruby (Adhearsion), C, Perl (Asterisk::AGI), etc. discover they can write Asterisk telephony applications just as easily and in the same languages. (The Adhearsion page, even if you're not a Ruby programmer, has a good overview and example applications if you're curious).
CommitteeCaller.com is a site that allows one person to target an entire congressional committee over the phone. The web application utilizes the open source Asterisk PBX system to connect you to every senator or house member on a particular committee. No more digging around the 'net entering zip-codes to retrieve phone numbers of representatives. CommitteeCaller.com automates the tedium of finding and dialing your favorite politicians.
Select a committee, enter in your phone number and click "Put me in touch with democracy!" and you'll be called by our system and sequentially patched through to the front office of each member on that committee. You can even rate how each call went; information that will enable us to rank representatives on how accountable and responsive they are to their constituents.
Once connected Committee Caller will tell you which representive you are calling, who their legislative director or chief of staff is, and what district they represent. At any point you can use the * to hang up the call and move on to the next one. Remember not to hang up after each call as you will have the opportunity to rate how your call went.