Being a webmaster myself I have been using several bookmarklets for managing and tracking things, here is a list of bookmarklets that I use on a day to day basis, many of them have been created by me as they were not available elsewhere.
These bookmarklets are specifically created for webmasters and range from useful Check Technorati Reactions- This bookmarklet will allow you to check the Technorati Rank for any website.
Compete Site Analytics – Check the site analytics for a website in Compete.
Quantcast Analytics – Check the site analytics at Quantcast.
Quarkbase Website Analysis – Know everything about a website at Quarkbase.
Sitonomy Analysis – Find the technologies that are being used by any website.
Social Networking Related Bookmarklets
Is This Page Stumbled? – This bookmarklet will allow you to check whether a page has been stumbled or not.
Share webpage – Allows you to share a webpage on popular social networking sites and more, powered by Shareaholic.
Hope these bookmarklets come in handy to you, please don’t forget to share your own bookmarklets with others, it might come in handy.