Helpfully, there are two guides available, one on your MBTI preferences (Myers Briggs) and how it influences your gift buying style, and the second one gives you help on buying gifts for others once you know or more likely guess their MBTI type. The beauty of the latter article is that you can probably work out who fits which type based on the descriptions given, so you won't need to ask me to profile all your friends, not that I wouldn't do it!
If you're wondering what MBTI is, then this little video is a fun explanation. Though I'm sure not everyone will love the My Little Pony references, I'm going to run with it anyway. As an MBTI practitioner I frequently find this tool helpful when working as a coach. Taking free tests is of course an option, and may give you some quick and brief insights which you will likely never remember. When I run MBTI sessions I often find there's an adjustment to be made when my client really understands the tool, in which case we can work out what their real preferences are and work out how that can help them in career decisions, relationships, or just generally looking after themselves.
If you are looking for a unique gift this year I have gift certificates available for MBTI or coaching. Just get in touch to discuss your needs.