I created a small form using which you can search the web for unicode devanagari words. It is very cumbersome to actually enter unicode devanagari characters using qwert keyboards, so I have adopted the phonetic transliteration scheme from Manogat website. Do give it a try:
http://amit.chakradeo.net/search/ (Link now removed, please see update below)
Start typing devanagari words phonetically and you will see unicode characters in the input area. When you hit enter, the phrase will be submitted to google.
Update: (2009-07-14) I have taken down my link now, as there are many more effective alternatives to do this. Check out the following pages from google:
Google Indic Transliteration (Marathi, Hindi)
Bookmarklets to transliterate any text element on any webpage.
A simple form for transliterating any text.