Please tell me if a webmaster gets a big list of major search engine then how they are going to get advantage of it.

there are many search engines
google
ask.com
my web search
yahoo
wikpedia
php nuke search
alchol soft search

Your question isn't very clear, so I'm giving u list of search engines:
www.yahoo.com
www.khoj.com
www.rediff.com
www.lycos.com
www.go.com
www.excite.com
www.altavista.com
www.snap.com
www.looksmart.com
www.askjeeves.com
www.goto.com
www.infoseek.com
www.hotbot.com
www.indolink.com
www.webcrawler.com
www.iwon.com
www.google.com
www.in.com
www.ask.com
http://search.creativecommons.org/
not all of them are exactly search engines, they let you search for stuff though. Creative Commons is special, it lets you search for music by uploading music similar to that you're looking for and more...
Good luck searching!