Websites to book Bus Tickets Online

http://www.redbus.in/
http://www.ticketvala.com/
http://www.makemytrip.com/bus-tickets/
http://www.travelyaari.com/
http://www.ticketgoose.com/
http://www.kpntravels.in/
http://www.abtxtravels.com/
http://www.apsrtc.gov.in/ (Buses by Andhra Pradesh Govt.)
http://www.ksrtc.in/AWATAROnline/ (Buses by Karnataka Govt.)
http://www.keralartc.com/ (Buses by Kerala Govt.)

Websites for booking Train tickets in Indian Railway

http://www.irctc.co.in (Recommended)
http://www.makemytrip.com/railways/
http://www.cleartrip.com/trains
http://www.yatra.com/

Websites for checking availability of trains in Indian Railway

http://www.erail.in/ (Recommended)
http://indiarailinfo.com/
http://indian-railways.rediff.com/
http://www.indiantrains.org/
http://www.indianrail.gov.in/