The SNP must win support to pass its spending plans early next year and, with numbers in the Scottish Parliament finely balanced, Ms MacDonald's vote could prove crucial.
During the recent budget debate, she voiced her hopes that government cash could be found to help refurbish Midlothian Snowsports Centre at Hillend, get the proposed white-water sports complex in Leith Docks up and running and help save Edinburgh's Dalry Swim Centre.
In previous years, Ms MacDonald has used budget negotiations to secure extra funding for Edinburgh in the form of an annual Capital City Supplement, recognising the city's special responsibilities, and cash for stonemason apprenticeships to ensure the survival of skills needed to preserve Edinburgh's historic buildings. Finance Secretary John Swinney said in the debate that he heard Ms MacDonald's points "loud and clear, as always".
Ms MacDonald has since had further meetings with ministers.
She said: "Once I spelled out the possibilities, I think they thought it worth investigating."
She said the ski centre and Dalry baths were valued public facilities which councils were finding difficult to keep open, but where a small amount of money would go a long way.
Hillend was a national facility which is currently being run by a small local authority, but around 500,000 could help with refurbishment and transform the way it is promoted. A community trust has already been suggested to run the centre if the council finds itself unable to afford it in future.
Dalry baths, under threat because of spending cuts, could be run by a co-operative or housing association-style organisation, Ms MacDonald suggested. She said a sum of less than 200,000 might be enough to keep the swim centre open until its long-term future could be decided.
The watersports complex at Leith had already been supported by people giving time and skills free to develop a business plan, but needed around 250,000 to get it to planning application level.
Ms MacDonald said: "These facilities are places that are always going to be under threat, so it's as well to look and see if there are other ways to pay for them. It's pump- priming money I'm asking for."
A Scottish Government spokesman said: "John Swinney will engage constructively on the budget process with all members, including Margo, although these are much tighter financial times."