I want to transmit real-time data via Attiny45/85 to the Internet. Is it possible? I can't find some about the Attiny45/85 with WIFI on Google. Could someone can give some advice? Thanks.
it does't make much sense to have ATtiny with WIFI. ATtiny is really "tiny" and the computing power you need for a WIFI is much higher (if you want TCP support for example). Actually the WIFI shield for the normal Arduino contains another controller which costs itself more than the Arduino nd is needed to implement the TCP IP stack. In reality it does not make much sense to have WIFI on Arduino either, with the same combined price of Arduino + shield you can buy a RaspberryPI + a WIFI dongle and you have a proper computer.
45/85 + Raspberry Pi + wifi dongle is the most cost effective/least hassle method I have found. The Raspberry Pi + wifi dongle is going to run you around $55 with shipping in the USA.