2002 - LootMail - Audio (phone) based interface to your email. Built on top of TellMe (back when they had a service pretty similar to Twilio today, based on VoiceXML. Died when TellMe killed off their "Extensions" program.
2004 - http://openpodcast.org - At the dawn of podcasting, I thought a podcast feed anyone could fill with audio content would be cool. The system was email-based: you sent an attached mp3 to submit@opencast.org and it would show up in the feed (there was also a phone number you could call to leave a recording). It was pretty popular as podcasting was getting off the ground. Adam Curry helped promote it.
2008 - http://quotably.com - Got the idea that a threaded view of twitter would be useful. Built it in a weekend, posted about it here on HN Sunday night, Arrington wrote a TC post, Scoble tweeted it, and next thing I knew there were upwards of 250K uniques Monday. I ended up killing it 6 months later because twitter turned off the firehose.
2004 - http://openpodcast.org - At the dawn of podcasting, I thought a podcast feed anyone could fill with audio content would be cool. The system was email-based: you sent an attached mp3 to submit@opencast.org and it would show up in the feed (there was also a phone number you could call to leave a recording). It was pretty popular as podcasting was getting off the ground. Adam Curry helped promote it.
2008 - http://quotably.com - Got the idea that a threaded view of twitter would be useful. Built it in a weekend, posted about it here on HN Sunday night, Arrington wrote a TC post, Scoble tweeted it, and next thing I knew there were upwards of 250K uniques Monday. I ended up killing it 6 months later because twitter turned off the firehose.