Google Wave is brand new service from Google and so it’s API. You may find Google Wave bit confusing up on first use but when you regularly use it will be very easy to handle it. Though Google Wave has many functions built in you can also add extra functions to this application through extensions and gadgets. Here are 10 most useful Google extensions and gadgets which you can add to your Wave to expand its boundaries...

1. Polly
Use this robot to create polls in a wave. You can store all the answers received online. Best for conducting online survey.
Polly Robot Address: polly-wave@appspot.com

2. Map Cluster Gadget
Map cluster enables participants to map themselves on the map. Clusters make it easy to locate groups close to each other.
Map Cluster for Google Wave: Map Cluster Gadget Import link

3. Ratings
You can use this gadget to get reviews and ratings from participants regarding any topic like movies, etc. It will automatically compute ratings and gives you tally of results in percent. Best for conducting online survey.
Ratings for Google Wave: Ratings Import Link

4. Stocky
If you want to know live stock prices for any stock symbol use this robot to get it. It will search for live stock prices in your blip that starts with $ and retrieves it.
Stocky Robot Address: stocky-wave@appspot.com

5. Calcbot
This will help you solve simple match calculations. It also allows you to use variables to solve simple mathematical expressions.
Calcbot Robot Address: calcbot@appspot.com

6. Buddy As a Service
This little wave  robot uses Yahoo YQL API and Google API  and other’s to search for the stuff you are looking for. Using simple commands you can search for weather forecast, translations, blog search, etc.
Buddy As a Service Robot Address: buddyasaservice@appspot.com

7. Embeddy
Embeddy is a wave robot which can generate a code to embed a wave in your website. You can use this widget to let your visitors know what your wave is all about.
Embeddy Robot Address: embeddy@appspot.com

8. Collaborative Sudoku
 Sudoku is one of the popular puzzle games which will help you to keep your mind sharp. Now you can play this game with your friends on Google Wave using this Wave extension. This is a multi-player Sudoku gadget.
Sudoku for Google Wave: Collaborative Sudoku Import link

9. Emoticony
Google Wave does not automatically replace text emotion representations with relevant images. Use this robot to replace text emotion symbols with cute looking emotion icons.
Emoticony Robot Address: emoticonbot@appspot.com

10. HTML
This gadget lets you to add HTML inside wave. This gadget is very useful for developers, programmers and geek lovers.
HTML for Google Wave: HTML Import link