I want to start making a temperature register with these specifications:
* Temperature range -10 celsius to 50 celsius
* register a Temperature sample every 10 minutes during 2 weeks and then send the stored samples to a PC in order to organize, massive storing and present the data
* Using a Pic 16F84 or a similar PIC
Yes, it's a VERY common application, and quite simple to do, you may find my tutorials helpful - depending how you plan measuring the temperature (I don't have any specific temperature tutorial).
Standard method for a data recorder would be to read analogue inputs (covered in tutorials), store it in EEPROM (covered in tutorials), and then transfer it via RS2s2 (covered in tutorials). If you use a thermistor them you just need to convert it to a suitable analogue voltage - however, there are some VERY nice LM series IC's, one gives an analogue output, so many mV per degree, and linear! - another gives a direct digital readout of the temperature.
See the joystick tutorial as well for reading the termistor. Works well. Of course you will need to setup the serial port and write a routine to dump the byte out to your PC program.