I use them often, they last forever, kind of like my 1982 Honda Civic. These apps are those Mac applications that do exactly what they’re supposed to, perfectly, everytime. My top two are the ones that have worked for me for years, at least since OS X 10.1.
GraphicConverter — converts any format to any other format, makes simple graphics so I rarely need Fireworks or Photoshop. Used to be shareware, now worth the $35.
And I added a new one today:
Paparazzi — takes a screenshot of an entire webpage, not just the visible part. I need a full shot of our POT webpage for a Board presentation, just in case the internet hookup isn’t working. You plug in the URL, click Capture!, then save as PNG, TIFF, JPG or PDF, with thumbnails or not. Simple and perfect, and free.