Lots of different options. If you don't want a million ideas, you might want to post some specifics ... such as source device, resolution, software, hardware, etc.
Here's a few ideas.
1. If you have a miniDV camcorder, you could use the A/D pass-thru to connect your analog source --> miniDV --> Mac (iMovie, FCE, FCP).
2. If you have an EyeTV device (or similar), they all pretty much have analog inputs (or dongles).
3. DV bridge (such as the the Canopus devices and some Pinnacle devices).
There are tons more techniques. Post some more info.
Good Luck