Thought I'd start a thread on useful Chrome Extensions now that they are easier to install through the new BETA here:
http://www.google.com/landing/chrome/beta/
My current ones are (and growing):
Google Mail Checker (https://chrome.google.com/extensions/detail/mihcahmgecmbnbcchbopgniflfhgnkff) (icon tells you how many new emails you have, clicking the icon opens a new tab to you your emails)
Last Pass (https://chrome.google.com/extensions/detail/hdokiejnpimakedhajhdlcegeplioahd) (password manager, explained elsewhere on these forums)
Wikipedia Lookup (https://chrome.google.com/extensions/detail/mpigaonbnnoiegabnipolkipehmgldba) (lookup the selected word on the current webpage and more...)
Mini Google Maps (https://chrome.google.com/extensions/detail/oeahddlmhbcabnnojadgimmiaaplfpfo)
Resolution Test (https://chrome.google.com/extensions/detail/idhfcdbheobinplaamokffboaccidbal) (for website developers)
Speed Tracer (https://chrome.google.com/extensions/detail/ognampngfcbddbfemdapefohjiobgbdl) (for website developers)
Web Developer Tools (https://chrome.google.com/extensions/detail/fbmlldeibipeppiabbdjajcneipfbocm) (for website developers)
Web Developer Mini (http://browsershots.org/?url=https://chrome.google.com/extensions/detail/dgmkbanfcdlllkbohlekikkgfbmkfolh) (for website developers)
Because they only install an icon next to the address bar, they don't take up much space in the browser either.
Researching more useful stuff, what about you?