Here are a guide to a few useful programs for Mac.
All of these downloads are free, and I have never had problems using them.
First off, There are the iPod video related programs.
Handbrake make it possible to rip a DVD to mpeg4 or H.264, the formats needed to play video on your iPod. It can also convert an already ripped VIDEO_TS file to the iPod formats. Its easy to use, and very userfriendly. I have used it for a while and never had a problem. This link provides a nice guide that tells you everything you need to know. Click the download link on the top of the site to install it on your computer.
http://howto.diveintomark.org/ipod-dvd-ripping-guide/
iSquint is a converting program that converts almost all videoformats to mpeg4 or H.264. Extremely easy to use, just drag a video you like to have on your iPod and click Start.
I discovered this program recently, and it works great. Download here:
http://www.isquint.org/
Then there are the DVD ripping related programs.
Mac The Ripper is an easy-to-use DVD ripper that lets you rip any DVD you would like, in full quality. You can save the DVD file to your computer and play with the DVD Player, or burn the files on a blank DVD using f. ex. Toast (see below). There is a manual, which you get with the program, where everything you need to know is provided. Download the program here:
http://www.versiontracker.com/dyn/moreinfo/macosx/22715
Toast 7 Titanium is the best program to copy, burn or backup DVDs or CDs. You can use this program to burn the files you have ripped using Mac The Ripper to a blank DVD and it will work on Macs, PCs and normal DVD players. Like every other Mac program, it is very userfriendly. Choose the "DVD-Video from VIDEO_TS" option and drag the VIDEO_TS folder into the window. If you rip a DVD that is over 4,7 gig, which is the size of normal blank DVDs, you can use a compressing feature on Toast to fit everything on one DVD. Here is a good torrent to download the program. Choose the second one. (I cant find the torrent I used, but if this one doesn't work, its easy to find another one. Just search google or something):
http://www.isohunt.com/torrents/toast+mac?ihs1=11&iho1=d&iht=5
If you dont have a torrent downloader, download BitTorrent. You can get it here:
http://www.bittorrent.com/download.html
If you want to play a ripped DVD that you have saved on your Mac, simply open DVD Player and hit apple+O. Then choose the VIDEO_TS folder that you want to play.
If you know more programs like this, then add them to this thread.