Aiseesoft iPhone 4 Software Pack for Mac is a nice mix of apps. It comes with DVD to iPhone 4 Converter for Mac, iPhone 4 Video Converter for Mac, iPhone 4 Transfer for Mac and iPhone 4 Ringtone Maker for Mac. With these utilities, you can rip DVD movies to your Mac, and convert pretty much any video file so that you can play it on your iPhone 4. In addition, you can manage it with the Transfer app to download any music or videos that you might have on your device. If you are tired of your stock ringtones, with the "Ringtone Maker" app, you will be able to cut out any part of a song and turn that into a new ringtone. You can get all of the apps in this suite separately, but it is much cheaper to buy this software pack.
The DVD ripper and the video converter both support the same output formats: MPEG-4, H.264, MOV and M4V. Those can be played not only by the iPhone 4, but also by the entire iPod and iPad lineup. Both apps also come with a video editor built-in that lets you trim and crop your videos and adjust their brightness, contrast and saturation.
In short, all the apps in this suite work well. They aren't the best out there, but they will suffice for every-day tasks.