Craig directed me to this piece today after I complimented him on the new version of Twitterrific for the iPhone, stating how much I love seeing different approaches to Twitter client design. I hadn’t seen his post (from December 2008) before today, but it’s a good read that gives insight into some of the decisions behind Twitteriffic’s design that are still applicable now.

Personally, I welcome this competition. Seeing the work of other developers whose work I respect and admire acts as an inspiration. Looking at how other developers tackle a problem domain often adds insight into solving similar issues with my own code. In other cases, it shows me how I don’t want to implement a feature (without the need to prototype.) In short, competition will make Twitterrific better.

Don’t be put off by the title if you’re not a GTD-type person. This list is a cornucopia of services built on top of Twitter, many that I’ve never heard of until now.

After three years on the web, Twitter has become more than just another micro-blogging client. A whole industry of web applications have sprung up to extend and capitalize on Twitter’s capabilities, from the ridiculously silly, to the gobsmackingly useful. If Twitter is not already a part of your daily life, these applications can give you a whole new perspective on the idea of Getting Things Done. There’s a lot you didn’t know you could do with 140 character spurts.

Update: As someone just pointed out to me… if you thought that was a decent list, check out the Twitter Fan Wiki. Whoah.