I have found Facebook and Twitter to be good for those. I have gigs on Fiverr and Fourer and I have received a lot of traffic from there. I would also suggest that you writing a couple of articles about making money with gigs, and then link to your microjob site. Good luck!!
You could try creating an RSS feed for your website, which you can Google to learn more about, essentially they are updates of the latest content of your website. You set up an RSS feed and then submit it to feed reading websites (again Google will help you find RSS feed sites, and google even has their own also) by submitting your feed to as many Feed Readers as you can you will create back links, and also have your sites latest content in as many locations as possible, making it more likely for people to stumble upon your website. Yes it does most certainly help get traffic, some times it may only get you a very small amount, sometimes it may be alot, it just Depends. But not only does it help generate traffic directly it also helps create backlinks, which helps you move up in Search Engines which indirectly helps increase traffic. Some website builders automatically have RSS feeds built in so by finding your RSS link you simply submit it to the Feed Reader site (an RSS link could look something like this "http: // your website name.com/index.php/type=rss" so basically its just a URL) so i suggest searching RSS topics about the platform your website is built on and you may find you have an automatic RSS feed and it will tell you the link to use. IF you do not have an automatic RSS feed on your platform (most do these days) you can create an RSS feed and manually update it, it is more effort then an automatic one but it is fairly simple you just log into your RSS account and just copy paste some content from your website in there ever day or couple of days (Google to find somewhere where you can set up an RSS account). Alternatively you can set up your own automatic RSS feed but this requires knowledge of PHP and XML scripting, it can be easy todo but without good knowledge in these languages i suggest staying away from setting up your own automatic feed and just doing it manually, that is if your platform doesn't have an automatic RSS feed already. I may of made an RSS feed sound complicated or high maintenance in this post, but i assure you it is extremely easy and very low maintenance and for the results it will give definitely well worth it. Also Setting up FaceBook for your website is a good idea, FaceBook also has an automatic RSS feed built into it, and it uses RSS 2.0 which includes pictures, so if you include pictures with posts on your FaceBook page, and you use Feed Readers that allow 2.0 (there is hundreds of them) you will have an RSS feed with pictures, this can be very useful if your site sells products. The only downside is the RSS feed will not create as many back links for your Website, and will Redirect to your FaceBook page instead of website. BUT in saying that by including the link to your actual website in your FaceBook posts people can click that link in the RSS feed to go directly to your website, and it will essentially create some back links for your site. This is a couple of posts put together from a thread were someone asked me the same questions, as i simply copy and pasted my threads together you can tell it might look like i'm having a conversation with my self These are my replies so it is my "original" content. Hope this helps you out.