Twittering
Since starting to use Twitter more I've found that I get more followers, some of these are friends and some are re-follows from interesting twitterers i started to follow.
However I am now finding that I get more annoying spammers who follow me just to promote their own site or think i might be interested in their tweeted advertisements.
One of the easiest ways to spot Twitter Spammers so you can block them is by the number of posts they have on their home page or by their follower, following ratio. i.e Following 6000, Followers 3
If anything will be death of twitter it could spam. I see it changing so they integrate more advanced optional security like facebook. You can keep your tweets private but I'm not sure of the point in that as its interesting to partake in and view trending and if your twitter was private you couldn't do this.