How send sensor data to webpage

Not sure if I need a ethernet shield?

Arduino - ArduinoEthernetShield

Arduino temperature and light data-logging and chart plotting webmonitor | codetorment

Sending temperature data from the arduino to a server | jankreuter

Arduino - BarometricPressureWebServer

Components I might need or would be useful?

Prototino ATMega328 kit

Make: Arduino

Arduino Mega ADK

Data logging shield for Arduino makes saving data to files on any FAT16 or FAT32 formatted SD card really easy. The included Real Time Clock timestamps all your data with the current time, so that you know precisely what happened and when!

Data logging shield for Arduino

Keep track of time stamping

DS1307 Real Time Clock breakout board kit

FTDI Friend v1.0

It could be conveniently used as sensor hub or integrated data collector for monitoring, tracking and etc. Seeeduino Stalker - Atmega 168 Arduino Ethernet Shield