I'm more interested in outright bans (or situations where federal government insists on trumping state legislation, even though the Constitution doesn't give it the authority to do so) than in the more typical blackmail via threats of withholding federal funding, although the more egregious examples of the latter are also worth noting.
1.
Congress Poised to Pass Bill Taking Away Right to Know What's in Your Food2.
Industries Get Quiet Protection From Lawsuits(Gift from GOP)3. Mandating drivers license requirements.
4.
Prohibiting states from issuing drivers' licenses to illegal immigrants.5. Prohibiting states from allowing civil unions.
6.
Stopping 'right-to-die' laws and interfering in state decisions
such as the Terri Schiavo case.
7.
/Documents%20and%20Settings/Joan%20Bokaer/My%20Documents/TheoWeb1/marijuana_times_feb1.html|Medical Marijuana laws.8. Supreme Court Intervention in Florida's decision about its own electors in the Presidential Election 2000.
9. CAFTA, prohibiting states from favoring local suppliers in their purchasing decisions.
Theocracywatch.org has a summary at
http://www.theocracywatch.org/states_rights2.htm of some state's rights issues.