India's rush of color, noise, and people will take you by surprise, no matter how much you try to prepare for it all. But I can recommend a few websites that ought to give you a handle on what you're in for when you visit. I've spent much of the past two years in Delhi, Chennai, Bangalore, and elsewhere in this fascinating country, and these sites were quite helpful.
IndiaMike: With its super-detailed coverage and sometimes overly opinionated contributors, this homage to all things Indian can be infuriating to newbies. But spend a bit of time here, and you'll be well rewarded. The site's exhaustive guides to the byzantine ways of the India's train system and its domestic airlines are incredibly useful.
What Am I Eating?: A good site to head to before leaving for just about anywhere in the world, this guide to the world's dishes and ingredients give equivalents in lots and lots of different dialects and languages. In a place as diverse as India, this site is a godsend.
Another Subcontinent: Written by current and former Indian residents as well as those with Indian heritage, this well designed website is tops in my book for information about food and many other essential parts of the region's many cultures.
Outlook Traveller: The web presence of a good travel magazine (keep an eye out for the paper version when you reach India). Because the places covered are meant to appeal to a middle-class Indian crowd, the selection is great for those travelers who want to wander off a bit from where most foreigners go. Inspiring pictures, too.
Incredible India: Although many of India's tourism sites remain out of date and frustratingly sparse, the country's main site is lush and full of good info. The site's Youtube page makes a good escape.