Facebook and Twitter from Gmail

Now you can use your Facebook and Twitter from your Gmail.
For enable this please follow below steps.

Go to Settings > Labs > enable "Add any gadget by URL"

After save changes, go again to Settings. you will see a new tab call"Gadgets"

Go to Settings > Gadgets > and copy below URL for Facebook and Twitter.

For Facebook: http://hosting.gmodules.com/ig/gadgets/file/104971404861070329537/facebook.xml
for Twitter: http://twittergadget.appspot.com/gadget-gmail.xml

After save changes you can go back to Gmail inbox.
now you will see Facebook and Twitter gadget top of invite a friend option.

For more gadget in Gmail, add below URL.
Wikipedia Search Gadget URL: http://www.google.com/ig/modules/wikipedia.xml 
Google Translate Gadget URL: http://www.google.com/ig/modules/dictionary.xml 
World Clock Gadget URL: http://gad.getpla.net/poly/clock.xml
Ask Word Gadget URL: http://www.openinventions.com/spellcheck/openinventions_spellcheck.xml
RTM Gadget URL: http://www.rememberthemilk.com/services/modules/googleig/rtm.xml 
Google Tasks Gadget URL: http://www.google.com/ig/modules/tasks.xml 
Google Calculator Gadget URL: http://calebegg.com/calc.xml 
Currency Converter Gadget URL: http://www.ac-markets.com/forex/currencyconverter.xml
Links To Google Services Gadget URL: http://blakewest.googlepages.com/googleservices.xml 

There are many other gadgets also that are use full and can be use in Gmail.