I abhor rats, mice, and roaches.
All three of which we found ourselves dealing with in our Brooklyn brownstone. It wasn't an infestation, but it was enough to get me out there looking for real solutions that involved repelling these creatures, not just managing their increasingly frequent guest appearances.
Two things worked miracles for us.
Rodents - 100% Peppermint Oil (it must be 100%, and it must be oil, not extract). It's extremely potent, burns the nostrils of rodents, thus repelling them, and is safe for all (save cats). Dab a few drops on cotton balls, and/or dilute an ounce in a cup of water in a spray bottle, and apply to places in your home that are known infestation points. Refresh once a month, if that. It's a real miracle. We haven't seen a single rodent in our apartment in a year, nor any of the tell tale signs. And it makes your house smell like Christmas year round.
Roaches - NYC roaches (I'm talking specifically about the American species) are basically as big as small children, with armor. Seriously, you can smash one with a shoe, hard, and half the time it will shake that off, and keep right on chucking. We were use to seeing an occasional one every couple months, but then after some bad rains they were popping up daily, sometimes more than once daily. Usually just one at a time, but it was enough, and my wife was at her whits end.
Amazon.com: Advion Roach Gel Bait 30 Gram 2 Tubes 666301: Patio, Lawn & Garden
This stuff is the real deal. It works within days. We haven't seen a single ****roach in months.