If you are a related to profession seo/linking etc, then you are going through many websites every day, you need to check IP,PR and other relevant things daily. I am facing so many problems while doing my work, I am using following tools while working. I need them every day so many times.
Domain IP Check
This is a good fire fox add-ons. I am using it for check websites; it shows all hidden info for a website in toolbar. Full description of all SeoQuake functions and parameters can be found on official site of addon: http://www.seoquake.com If you are using Mozila Firefox download it.
I hope you will like the above information. If you have some good tools related to seo/linking profession then please let me know here.