1) My Yahoo Page

http://tinyurl.com/hgj5f

Click on "ADD" button next to Currency Converter link to add the module to my.yahoo.com page.
Bookmark or make the my.yahoo.com page as your home page.

2) Yahoo Messenger

http://finance.yahoo.com/q?s=USDINR=X

Click on the link "Add USDINR=X to Portfolio" and add it to yahoo messenger. Next time whenever you want to check the USD prices check the stocks tab of your yahoo messenger.

3) Command line interface

If you have installed yahoo shortcuts from http://yahooshortcuts.com then type the following command in the yahoo search box.

If you want to convert one dollar to Rupee,

!ys cur -from USD -to INR

Or if you want to convert more than 1 dollar...

or if you want to convert

!ys curConv -amt 1000 -from USD -to INR
!ys currencyconv -amt 1000 -from USD -to INR