Memset's is.gd is a site that provides one-click URL shortening option without entering any captcha. It allows you to customize your new shortened URL with options of standard format, lower case and pronounceable words. One of unique feature of is.gd is its QR code generator for each of its shortened links. An optional log statistics is provided that provides analytics based on country, browser, platform, date and time. It also displays a list of top referrers and their total number of hits. This service is associated with v.gd for shorter links and default preview pages. Its firefox plug-in can be used for instant shortening of URLs during browsing. It also supports twitter clients and various open source add-ons, apps and platforms.
Bitly doesnt offer this service in their free plan. They consider it to be a premium feature and have made it available only to their paying customers.Another reason for this is to prevent spammers from abusing Bitly. "Bitly hasURL Shortening Tools Bitly