Foxit PDF IFilter (for 32-bit Windows, for x64 Windows):
http://www.foxitsoftware.com/pdf/ifilter/index.html#downifilter

Adobe PDF IFilter v6.0:
http://www.adobe.com/support/downloads/detail.jsp?ftpID=2611

Foxit PDF IFilter:
http://www.foxitsoftware.com/pdf/ifilter/

Audio Video IFilter - WMA, WMV, MP3 IFilter - [free for non-commercial use and 30-day trial for commercial use]:
http://aimingtech.com/av_ifilter/download.htm

JPEG IFilter - [free for non-commercial use and 30-day trial for commercial use]:
http://aimingtech.com/jpeg_ifilter/download.htm

CHM IFilter:
http://citeknet.com/download.aspx?url=ifilters/CHM/Citeknet.CHM.IFilter.Setup-1.5.3.msi

CAB IFilter:
http://citeknet.com/download.aspx?url=ifilters/CAB/Citeknet.CAB.IFilter.Setup-1.5.3.msi

EXE IFilter:
http://citeknet.com/download.aspx?url=ifilters/EXE/Citeknet.EXE.IFilter.Setup-1.5.3.msi

HLP IFilter:
http://citeknet.com/download.aspx?url=ifilters/HLP/Citeknet.HLP.IFilter.Setup-1.5.3.msi

RAR IFilter:
http://citeknet.com/download.aspx?url=ifilters/RAR/Citeknet.RAR.IFilter.Setup-1.5.3.msi

ZIP IFilter:
http://citeknet.com/download.aspx?url=ifilters/ZIP/Citeknet.ZIP.IFilter.Setup-1.5.3.msi

RTF IFilter:
http://download.microsoft.com/download/SharePointPortalServer/Utility/1/NT5/EN-US/RTF.exe

IFilter - Add-in for Outlook saved mail (.msg file) indexing:
http://gallery.live.com/liveItemDetail.aspx?li=71ffbf5d-9595-457f-9463-db5dd0fd781e&l=3

Mails IFilters [Thunderbird / Mozilla / Eudora Filter]:
http://citeknet.com/download.aspx?url=protocolhandlers/mailaddin/Citeknet.WDS.Mail.Addin.Setup-0.7.msi

DWG and DXF files are added up to AutoCAD version 2008:
http://www.dwgifilter.com

Visio IFilter 2003 Add-in: Text Search in Visio Files:
http://www.microsoft.com/downloads/details.aspx?familyid=dcee9e09-448b-4386-b901-efea29cac808&displaylang=en

Add-in for Lotus Notes [to index the content of Lotus Notes e-mail, contacts, calendar items, and journal items]:
http://www.microsoft.com/downloads/details.aspx?FamilyId=AC768E36-BE57-4306-966C-5089B0C4D50E&displaylang=en


Microsoft Filter Pack [This Filter Pack includes IFilters for the following formats: .docx, .docm, .pptx, .pptm, .xlsx, .xlsm, .xlsb, .zip, .one, .vdx, .vsd, .vss, .vst, .vdx, .vsx, and .vtx]:
http://www.microsoft.com/downloads/details.aspx?FamilyId=60C92A37-719C-4077-B5C6-CAC34F4227CC&displaylang=en#filelist

other IFilters links:
http://citeknet.com/

other IFilters links:
http://www.ifiltershop.com/

other IFilters links:
http://www.ghacks.net/2007/03/06/new-filters-for-vista-search/

other IFilters links:
http://www.ifilter.org


Debugging IFilters with WDS 3.0 and Windows Vista:
http://blogs.msdn.com/ifilter/archive/2007/02/06/debugging-ifilters-with-wds-3-0-and-windows-vista.aspx