Why Fandom Can't Have Nice Things: As much as celebrities have taken to Twitter, the very uncensored and unfiltered nature of it have also created a few enemies, due in part to some fans who air their grievances directly to the creators themselves. Some examples include people attached to Merlin, Doctor Who, and Sherlock are rather notorious examples.
Some useful Twitter utilities:
Favstar, which keeps track of a user's favorited and retweeted tweets.
Twilog, which provides an online archive of your tweets and provides some useful statistics (like tweets sent on each day and each month, times you've mentioned a user). Although Twitter itself provides a tweet archive service, Twilog's archival services are in semi-real time, while official tweet archives have to be downloaded completely every time you want an updated version. Unfortunately, the site is in Japanese only, and you can't use it if your account is set to protected mode.
Favolog, from the same developer, keeps track of the tweets you've favorited. This is particularly useful in that Twitter does not provide any official favorite archive services.
Twiprofile, a service for creating an extended Twitter bio. In addition, it provides stats about your account, such as date and time of account creation (in Japan Standard Time) and average number of tweets per day, and you can add tags to yourself so like-interested users can follow you. Japanese-only, and has the unfortunate bug of splitting lines in mid-word, as the website is not meant to be used in English.