The code I use on my sites is all made by me. I only use three 3rd Party scripts:
Generally, I don't like working with 3rd Party apps. No matter if I'm reinventing the wheel, I prefer working with my own code. The only reason I use the scripts above is because it'd be a
lot of work to make something better (Whereas I think it's impossible to make a templating engine better than Smarty, or a forum software better than vBulletin).