Some tools I have made and or modified myself. I notch out regular ribs with my dremel to achieve a small bead at the base o my bowls. I cobbled together a measuring stick for width and height for mugs - from bamboo skewers and some waxy thread.
I have this one tool, not really sure where it had come from but I have had it for many years. It's called a "Yumi". It's a little harp - like a cutter. I finally found the source of it and was so thrilled. I ordered up a backup one for me and an extra for a fellow potter that loves it too.
It came from bambootools
They have a nice assortment of other tools - and I also discovered they have some good videos on YouTube. just search bambootools.com (warning: music is rather tacky).
This little tool is great for a multitude of jobs, but my favorite is cutting up pulled handles and then cutting off the excess clay on the cup. Being on their site was a little like going to Target. I just needed one item, but I walk away with a lot more.
On this afternoon of web shopping for pottery stuff I also ordered up a few underglaze "markers" I want to see if they really can write better than the needle tipped bottles. Will report back on these markers.