Hi!! I'm Ym new to this site.
I heard globalCALCnet and Gossamer let you go online. Is that true?! What functions are available? Are there restrictions? Where can I buy one of them?

you don't have to buy anything. They are both free. I don't know how they work, but I do know that gosammer can be downloaded here.

Gossamer and globalCALCnet are both free. Gossamer is a web browser for TI-83+ and TI-84+ graphing calculators, and globalCALCnet is a way to connect calculators over the internet. It's part of CALCnet, a networking protocol built into the Doors CS shell. I maintain a central gCn server/bridge that lets Gossamer access the internet via gCn. The thing you DO need is a globalCALCnet bridge, which can be an Arduino or Direct USB (which is still glitchy)

:: Gossamer 1.0
:: Doors CS 7.2 Beta 2 is what you need for gCn/CALCnet
:: globalCALCnet documentation

Thank you for your replies!
My bad, I was thinking of a calculator that can connect to Wifi... but there is no such thing, is there?

There is not.

Not yet. There are some projects for wireless CALCnet, one of which is my own, and BrandonW has been working on and off with Bluetooth and WiFi USB drivers for the TI-84+/SE, but nothing currently is available.

If a calculator could be connected to Wifi, it would be banned on standardized tests. However, it would be cool if someone made a Wifi adapter...

Indeed, and that's the eventual hope for globalCALCnet. People have been exploring the MSP430's wireless communication, Zigbees, and even Bluetooth before, but no one has had the time to complete one of the implementations.

thanks guys... by the way, i heard we can download wolflamalpha or mathematica on a TI calculator, do u know if that's true? i looked online but couldn't find it

No, that's patently false. Perhaps I should make an Octave interface for CALCnet or a clipped version of WolframAlpha, but currently no such thing exists.