Quote from: BitcoinTTrader on Today at 02:05:29 AM

Is there an online mining app or a downloadable app that will allow me to chain these three Macs together and have a minuscule mining platform?

Electricity for me is absolutely free, with 45 Sunpower panels on my roof.

As said, you cannot mine bitcoin with those. It means that they'll run, but you'll receive nothing because of the high difficulty.
But you can mine altcoins.

I suggest you ask for more details in altcoin mining sub, but you may be able to mine Monero or similar coins and exchange if you want into bitcoin.
You will probably need a proper stand alone application, not in-browser one which may be blocked and may have lower performance too. Just make sure you ask on the forum before downloading, so you don't download something useless or harmful (although it may not be the case for iMac).

Also keep in mind that mining is hardware intensive too and you should make sure that your iMacs' fans will handle the load. We don't want to burn down the place for a few pennies, don't we?

However, please ask in altcoin mining for more details, including what miner and what pool to use.