Appraisal Districts:

Travis County: http://www.traviscad.org/
Williamson County: http://www.wcad.org
Bastrop County: http://www.bastropcad.org/
Hays County: http://www.hayscad.com/
Burnet County: http://www.txcountydata.com/

Forms:

Residential Homestead, Over 65 & Disability Exemption http://www.window.state.tx.us/taxinfo/taxforms/50-114.pdf
Disabled Veteran Exemption http://www.window.state.tx.us/taxinfo/taxforms/50-135.pdf
Travis County Name or Address Correction http://www.traviscad.org/pdfInameadd02.pdf
Williamson County Name or Address Correction http://www.wcad.org/appraisal/publicaccess/Forms/NameAdrsCorrform.pf

Assessor Collectors:

Travis County http://www.traviscountytax.org/goHome.jsf
Williamson County www.wilco.org
Bastrop County http://www.bastroptac.com/
Hays County http://www.co.hays.tx.us/
Round Rock ISD https://actweb.acttax.com/actwebdev/rrock/index.jsp

Tax Rates:

Travis County http://www.co.travis.tx.us/tax _assessor/rates/default.asp
Williamson County http://www.wcad.org/Appraisal/PublicAccess/Forms/taxrates.pdf
Hays County http://hayscountytax.coml_lileUploads/forms/TaxRates2010.pdf
           
Texas Comptroller:

Texas 2009 Property Tax Code http://www.window.state.tx.us/taxinfo/proptax/96-297-09.pdf
Taxpayers' Rights, Remedies & Responsibilities http://www.window.state.tx.us/taxinfo/proptax/tx96295_00/index.htm
Tax Laws, Rules and Policies http://www.window.state.tx.us/taxes/lawsrulespolicies.html