I almost didn't list Swagbucks here because, while it's a great rewards site, they list in their terms that you can't expect for up to 10 days after you cash out. However, it's still an option to earn fast cash because some people report getting paid much faster than this. You can redeem you SB (Swagbucks) for Amazon codes, Paypal cash, and gift cards to popular merchandisers among other things. These points build up quickly thanks the the large number of things you can do on the site to earn. I've used this site and been paid many times.
Pinecone is one of the best survey panels out there for earning fast cash, and they pay quickly — usually by the next day — for the surveys you complete. The surveys don't come every week, but it's a nice little bonus when they do because of how fast they pay. Right now Pinecone is open, but there is no guarantee you'll get in just depending on what demographic they need right now.
PrizeRebel is another survey website that offers payout options via PayPal. You can cash out as little as 500 points to earn $5. PrizeRebel offers a wide range of PayPal redemption options starting at $5 on up to $100 payout amounts. You can also request a custom payout based on the specific amount of points that you have which is a nice touch. Another bonus is that PrizeRebel occasionally offers a slight discount on the point redemptions as well. For example, instead of spending 500 points to redeem $5 it ends up being 485 points instead (a 3% bonus).
Fiverr is a popular platform for offering services. You can create your own Gigs to have available for sale. As the name suggests, Gigs are available to purchase starting at $5 though you can offer upsells to increase your earnings. You do need to wait 14 days between completing a Gig to being able to withdraw your earnings by PayPal. There are fees associated with these transactions.