I'm studying the Chinese Link 1 textbook, and when I go into a lesson to look at the words there, some words have green dots next to them. Here's a photo:

http://i.imgur.com/fxqD8uA.png

I know the ones with the red circle thing are banned, but some of the rest have green dots and some of the rest have nothing. What gives?

It marks, what you have learned so far and what not. Go to the top and press more, next to progress, and you'll see the details:
W = writing
T = tone
P = pinyin
D = definition
The color will also tell you, to which degree you have learned it. If the area is grey, it means it is added to your list, but not learned so far.

Oh, I see! Thanks very much!

I'm curious - what is your philosophy on the words you have banned?

They were words that I already knew really well and didn't want to be tested on again. I'd taken Mandarin for two years in high school, but last year I started over from the beginning in college, where they had us learn traditional characters. Since I started using Skritter halfway through the year, I wanted to get through the beginning characters that I already knew quickly and just banned them.

With the end of the semester, I've just switched back to simplified, so I guess that's why so many of the words are un-introduced. The only ones with the green dots are the ones that are the same in traditional and simplified, like 名字 and 姓.

Makes sense - I thought about doing this for a while, but then didn't as can forward to next item if you know a word, rather than write it out, so doesn't take too much time to get known words into Skritter's SRS with long intervals.

Switching between simplified/traditional like that sounds like a pain, hopefully can find classes that stick to one or the other! Although I know some people learn both at the same time and swear by it.