Making a lot of money within only 2 days can be tricky, but it can be done, if you're willing to put in the effort.
Probably the best way would come as a surprise to many, but a garage sale can rack up a big pile of extra cash, and as a bonus, de-clutter your home at the same time.
Look around for anything you don't use anymore; clothing, old electronics, kitchenware, furniture, books, toys, tools, antiques... All these things, even sold at pennies on the dollar, can bring in a lot of money if you find enough stuff to sell.
In that same vein, antiques and clothing in near new condition can be sold at consignment shops, used books are often bought by book stores, and entertainment stores buy used video games, DVDs, and CDs.
In "serious business" garage sale news, some communities set up town-wide garage sales to bring in tons of people looking to buy. Northlake, NJ just announced signing up almost 160 residents for theirs!