You can make money with Joomla Affiliate Programs. Many Joomla developers offers Joomla Affiliates Programs for thei services and give you commisions to promote their services. Here is a Joomla Affiliate Programs list.

RocketTheme - You will make 20% of every membership that is generated.

iJoomla - 20% of all sales you deliver. $9.00 USD - Minimum balance required for payout.

Alledia - $10.00 USD for all sales you deliver. $5.00 USD - Minimum balance required for payout.

JoomlArt - 20% of all sales you deliver.  $100.00 USD - Minimum balance required for payout.

Phil Taylor - 20% of each sale delivered. £35.00 GBP - Minimum balance required for payout.

Shape 5 - 20% of each sale delivered. $100.00 USD - Minimum balance required for payout.

Joomlashack - 10% of all sales you deliver. $50.00 USD - Minimum balance required for payout.

BuyHttp - $25.00 USD for all sales you deliver. $100.00 USD - Minimum balance required for payout.