Here are some of my favorite Chrome extensions. Perhaps others can comment on their favorites.
Read It Later
Good to flag a link you wish to read later. Has a flag button and a go to the read it later links you tagged. I use this for links I do not want to bookmark immediately and to just want to "read later".
Nice status button grading the safety of the link/site in green, orange, and red. The grading comes from the mutual community of WOT users. Help you avoid some bad sites.
This is my all time favorite extension and you must give it a try. It basically gives you a quick facility into just about all the social sites selectively. You can use the extension button and select what you want to do with the current page, for example send to twitter. Or, set up hot-keys. I, for example, set up alt-m to mail a link, alt-s to share a link, and alt-t to twitter a link. Very quick to set up.
Google Mail Checker
Nice icon that gives you the count of unread emails in your gmail account. Keeps you from having to check your inbox tab.
IETab - windows only
Allows you to have an IE tab within chrome. Helpful for those sites that only work with IE. You can set up auto-urls so when you got to a particular site, it always loads in an IE Tab. For example, when I go to msdn, I have it set to load in an IE tab versus a chrome tab.
There are many weather extensions but I have found the Accuweather to be concise and gives me the information I want to see.
Too Many Tabs for Chrome
If you have a lot of tabs open, it gives you quick access visually in an Aero like style to select the tab you want. Chrome has many quick hot-keys too though.
Monitor a page for changes at the frequency you select. For example, I use this to monitor the downloads page for my Buffalo Router. I want to know when new firmware comes out and this extension takes care of it more me so I do not have to manually check. Of course RSS would work if they had it for downloads at the Buffalo Support Site.
Allows you to manually or automatically switch your proxy. You might wonder how I use this so I will explain. I have my DHCP server on my home network to dole out the OpenDNS servers for content filtering. This forces all of the nodes on the network through OpenDNS. However, there are a few social sites that my wife and I want to get to but still want to block my son from. So, I spun up squid on my firewall (FreeBSD/IP Filter) and configured squid to use the standard DNS servers from my service provider, AT&T. So when my wife wants to go to facebook, her ProxySwitch rule kicks in and uses squid to access facebook versus going direct and using OpenDNS servers(which are configured to block social sites). At this time, my son is young enough he does not know how to by pass my parental filtering. In time, he will get old enough that I will have to tighten things up.
Currently in my "try it out mode". I migrated my bookmarks from delicious to yourversion and I am trying out yourversion. It has some nice features and also lacks some features. See my previous blog post. The chrome extension for yourversion duplicates functionality of shareaholic. However, shareaholic does not have a hook for yourversion, hence I have to use it.
I'd like to hear from others on their favorite extensions.