Those that have recently switched to Mac from Windows often miss certain applications that aren't available on OS X. One of these is Nero for burning DVDs and CDs. Fear not however because there are alternatives to Nero on Mac to burn discs with.
Roxio Toast is the most comparable burning suite to Nero. Like Nero - which now calls itself a "multimedia suite" - Toast offers more than just burning including video and audio editing and even management of your TiVo recorded TV shows. You can also create hybrid discs with Roxio Toast that will work on both Macs and PC.
SimplyBurns isn't as sophisticated as Roxio Toast but for simple burning tasks, it's perfect. SimplyBurns has a simple GUI which takes you step-by-step through the process of burning data, audio, copying, ripping and image burning. Best of all, unlike Toast it's completely free.
Burn is probably the simplest of the lot. I use it regularly for basic burning because it's far easier and better than using OS X's in built Disk Utility, especially for burning ISO images. It's also excellent for burning video files as it gives you presets for VCD, SVCD, DVD-Video and DivX files meaning it does all the conversion and encoding for you. Oh, and it's free.