Is there any alternative for Windows gadgets in Ubuntu?

There are few options:

1. Screenlets

   Screenlets are the Linux alternative for "Windows Gadgets". Screenlets are small owner-drawn applications (written in Python) that can be described as "the virtual representation of things lying/standing around on your desk". Sticky notes, clocks, rulers, ... the possibilities are endless.

   

   Hare's a preview of a weather screenlet:

   

   To install Screenlets, open terminal by hitting Ctrl+T and run following commands:

   sudo apt-get install screenlets
   

   To install a complete pack of Screenlets:

   sudo apt-get install screenlets-pack-all
   

   Some sources to download Screenlets: Gnome-look, KDE-look.

2. Cairo-Dock

   Cairo-Dock is an attractive, Lightweight eye-candy dock to launch your applications. I'm mentioning it hare because of it's ability to add add-ons. It comes bundled with many applets including this weather applet. You can use applets inside dock or detach and use them as gadgets.

   

   To install Cairo-Dock, open terminal by hitting Ctrl+T and run following command:

   sudo apt-get install cairo-dock
   

   You can find some third party add-ons hare.

3. Conky

   Conky is an advanced, Highly configurable system monitor for Linux. It's little hard to configure, Specially for new users. Hare's an example of conky

   

   Follow these steps to setup HTC Conky:

   1. To install Conky, open terminal by hitting Ctrl+T and run one of following commands:

      To install a standard conky:

      sudo apt-get install conky-std
      

      To install a full conky with most compile options enabled:

      sudo apt-get install conky-all
      

   2. Download Conky HTC Home and extract it.

   3. Press Ctrl+H to show hidden files. Copy ".conky" from downloaded folder to your home directory.

   4. Open the "fonts" folder and copy all the fonts to Home/.fonts/

   5. Go to AccuWeather and find your location and copy web address.

   6. open Home/.conky/htc_home/accuweather/accuw_script with text editor and replace the location address with the web address you just copied from AccuWeather.

To put conky into startup applications, Hit super key (Windows key) and search for "starup applications" and open it.

Click on add, and fill respective fields as follow:

Name: HTC - Conky  
Command: bash -c "sleep 15; conky -c $HOME/.Conky/htc_home/conkyrc"  
Comment: Conky

and save it.

To start Conky for the first time, Hit Alt+F2 and run the following command:

conky -c ~/.Conky/htc_home/conkyrc

That's it...!

For more Coky themes visit: DeviantArt, Arch Forums, Web UPD8, Ubuntu Forums.

Plexydesk is frigging awesome. This app creats an environment for widgets for Ubuntu, like Plasma of KDE.

Don't ever bother of Screenlets or gDesklets, they are out-of-dated.

I installed conky-Lua.

Step by step instructions are in http://xchamitha.blogspot.co.uk/2012/11/adding-gadgets-to-ubuntu-1210-desktop.html