The cross-references search engines

Chipfind : http://www.chipfind.net/crossreference/

TI : http://www.ti.com/sitesearch/docs/crossreferencesearch.tsp

NXP : http://www.nxp.com/xref/nxp?typenumber=

ST : http://www.st.com

Maxim : http://www.maximintegrated.com/en/products/cross_reference/index.mvp

Freescale : http://www.freescale.com/webapp/crosscheck/competitorXRef.sp?fsrch=1&sr=2&pageNum=1

ONSemi : http://www.onsemi.com/PowerSolutions/extSearch.do?query=&param1=type&param1_val=xref_m1

Infineon : http://www.infineon.com/cms/en/product/crossReferenceSearch.html?q=cross%20reference

Toshiba : http://toshiba.semicon-storage.com/ap-en/design-support/search/xrefSearch.html

Renesas : http://www.renesas.com/req/other_product_search.do?event=otherProductSearch

ADI : http://www.analog.com/cpsearch/CrossReferenceSearch.aspx