You should now be able to set up a new application to query Twitter, create the proper OAuth tokens using the OAuth library on node.js, and build a bubble chart. The Twitter API is rich and has many more potential visualizations lurking in it. I'm sure that we could come up with a couple of dozen potential visualizations. There is no better way to learn than through experimenting with the API, so don't be afraid to get messy.
In the next chapter we'll take a look at visualizations of data on the popular question and answer site, Stack Overflow. Their API is largely an open one which doesn't require authentication for most queries, so we should have a brief reprieve from having to use OAuth and even node.js.