I use Flickr mostly for a set of abstract patterns. This pattern, "diamond limit square”, resulted in the most tags. Comparing several images and their common tags gives a better idea of the image features and statistics that result in those tags:
A slightly less abstract photograph, “I Phone” resulted in only a few tags:
Twitter recently allowed some control over how account holders are sliced, diced and tracked, and your “interest” categories are available.
Interests from Twitter
These are some of the interests matched to you based on your profile and activity. You can adjust them if something doesn't look right.
You have 54 interests from Twitter.
Interests from partners
Twitter's partners build audiences around shopping decisions, lifestyle, and other online and offline behaviors.
You have 23 interests from partners.
Below are my 54 “interests from Twitter”. The 23 “interests from partners” is demographically oriented, and I'm not comfortable posting that willy-nilly. It’s all used for monetizing our eyeballs through predictive analytics, and this only reflects a small fraction, through a foggy window, of the personal data Twitter and other corporations curate and exploit.