For accurate cooking temperature you really are going to have to invest in a good cooking thermometer. If you are doing large joints of meat, often different parts of the meat will cook at different temperatures too, so its important to be able to check how much the meat has cooked.
For instance for smoking, accurate knowledge and control of the temperature of you smoker is essential to get the best out of the smoker and the meat. You may need different kinds of thermometers depending on the type of cooking you do. Leave in thermometers are great if you want to be able to see the tempertaure of the meat all the time. Instant read thermometers work well though if you need to check the meat in various places. The down side is if you are using an oven or smoker you will need to open the door and disturb the cooking process.