I've been thinking of building a fiverr clone, but with Bitcoins and possibly other cryptocurrencies as the payment method. Has this been done before?

BTC-E. They offer a very wide range of deposit and withdrawal options, so it can be fast if you want to get funds in quickly. Withdrawing fiat is very expensive though. I've seen a lot of people fretting and posting warnings about BTC-E disappearing into the night at any moment, but they've been around for quite a while now. MtGox had an office address and were setup legitimately in the public eye, and look what happened to them. I digress, but sometimes, the warnings get me irate because we see lots of new scam sites coming up every day, and people are willing to give them their money.

As for fiat withdrawals, I've been using Bitstamp, where I have my identity and address verified. Significantly cheaper than BTC-E.

On an unrelated note, I noticed a number of glaring spelling errors on the site. Is there a curated list of legit Bitcoin investment programmes?

It is possible to maintain complete anonymity if you're very careful, but the problem is we are human. At some point, someone is bound to make a mistake sooner or later, which may result in identifying information being leaked/released.

Faucets are literally no good, except if you've got all the time in the world. It would be nice to have something like fiverr, but with Bitcoins.