I’m a PhD student using Tabbles to categorise all my references in preparation for my writing-up stage. The old folder system in Windows Explorer was really hampering my work, since many academic references discuss subjects relevant to different aspects of my research, so it was a nightmare remembering in which folder I had put them and avoiding having duplicates all over the place. Tabbles has sorted this completely now!
In response to one of the posters above, I also use two computers (a desktop in my PhD office and a laptop for when I am out and about). I have devised a system that works perfectly in conjunction with Tabbles. I had always synchronised my desktop and my laptop. I did this using a synchronisation program called SyncBack via a VPN connection to my university’s server. This looked at my two folders, found differences and synchronised the two. The trick, I realised, to make this all work with Tabbles was to ensure that both my desktop files and my laptop files had exactly the same path. This meant creating a new drive partition on my laptop, and giving it the same letter (H:) as my desktop drive. The other "trick" is to change the Tabbles database path (File>Tabbles’ databases>Change database path) to, say, H:TabblesDatabase, so that it is stored with the files you are synchronising, and is therefore kept up-to-date using SyncBack.
I hope this is useful to anyone trying to do something similar. Just a final thanks to Andrea and the team for a great job.