Our mashup Info from Twitter has been updated. It lets you pickup from the social graph other resources, associated with the given twitter account. It is a dead simple way to discover who is your new follower and/or who you follow to in Twitter. WHOIS for Twitter.
You can directly type a name for twitter account on the mashup's page or pass it as a parameter:
where some_twitter_name is a name for Twitter account. E.g.:
Also here you can find an appropriate bookmarklet for this service.
P.S. see also:
WHOIS for Facebook - Social Graph Directory
Social Graph and Social links for sites