I have had success pouring boiling water on them or spraying with vinegar. Either would kill your other plants, as well, though, so be carefull. Boiling water seems to work better than vinegar for dandilions (very satisfying, btw), but will burn your lawn if you try it there and I couldn't find anything that would work for horsetails. I also tried both for ants but pouring dishsoap down the holes seemed to work best for those, and does not hurt the plants.
Canadian mama to A (C/S May 2004) and R (induced VBAC Dec 2007) expecting #3 in July. Currently obsessing over permaculture, photography and beekeeping.