Go buy a burger, some chips and an orange juice. Eat, relax for a few minutes and then go on google and search for 'internet marketing and SEO and start reading. I can't really see the u$ 20 doing much use elsewhere.
You can't do anything with $20. Save your money and read some useful info about SEO. You will get more traffic this way
depends how active you want your forum i'd spend that $20 on a referral contest, or a posting competition
I wouldn't spend it at all, i find that submitting to small directories is usesells because everyone uses msn, yahoo and google, SEO takes a long time. Submit articles to sites about your forums niche, then let them know you have more info at your forum, also start adding people from myspace from the same niche. You could do this by adding people from a specific group. Do the same for facebook. Of course this is for fast traffic, if you have patience go for SEO
Paid posters definately, nobody likes posting contests unless theres lots of money up for offer, you can't do much with $20, maybe buy some sig links?
What about word of mouth marketing? That can be really useful. Tell all your friends and family - that way it will have a viral effect.
Try this. Make a flyer that is about 3.5" wide by 3.5" long. You can fit 6 add on one sheet of paper that way. Go to Kinkos, or your local copier place and get 340 copies of it. That should be about $17 at 5 cents a sheet. Then have them cut it. That should cost about $1.00 a cut so 3 cuts, and you have spent $20. Now you have 340X6, or 2,040 flyers. Deliver them by hand, and make everyone count. Don't just leave them at door steps. If you go to school you will probably have a large surge of traffic at your website that night after passing them out!
Stick the $20 back in your pocket. Congratulate yourself because your site has made it's first $20 in profit! In other words... read DP, and don't pay for something that you can do for free. Directory Submissions Social Bookmarking Forum Sig Free links [Freebie section]