A few days before the Ugandan election in 2006, I built UgandaWitness.org. It allowed people to submit their experiences of the elections and report electoral abuses over the internet. Without a marketing budget, and with internet access still limited to a minority, it only received a small number of reports from citizens. But it's primary use was as an information portal - bringing together reports of abuses in papers and on radio, in both government and opposition outlets.
The breakthrough for citizen activist websites was Ushahidi, built in the midst of Kenya's post election violence in 2008. It allowed people to report what was going on by SMS, broadening access significantly. It was famously used in Haiti and other disasters and conflicts, but each time Ushahidi was implemented it seemed to be in an after-the-fact situation.
In 2011 a consortium of Ugandan NGOs decided to use this idea in the run up to the election, in a pre-conflict environment, another first. UgandaWatch was used to report issues with the entire electoral process from voter registration to results tallying. It was promoted with a radio campaign and the flyers below. An evaluation can be found here.