I think we need to tier types of rewards otherwise this could turn into a monster of a problem.
Rewards are great. No doubt about it. But we must ensure that the types of rewards given not only reflect the substance of what has been done to earn it but also don't become so easily available that they lose their value.
For example (I apologise for the lack of technical knowledge of whether such things can be done in these suggestions):
Articles that achieve a monthly prize (Such as Article of the Month) might be awarded with all of their posts being covered in Banana (placeholder) decorations which last until the next Article of the month award is given out. A separate page on the profile would record the award and possibly a second banner next to the contributor ribbon- red ribbon (I deliberately chose red as this normally reflects second place whereas the blue ribbon would reflect the first place Article of the year). I very strongly believe we should not get into cash level handouts on a monthly basis unless it remains very token, but should use an inhouse system.
Articles that become recognised for their merits could also be adjusted to reflect a graphic stamp of approval for a valuable article (which while it may not have won a monthly prize was of sufficiently high enough standard (as in gone the extra mile) to earn this recognition as well an addendum to the profile page.
Quarterly reviews if we do generate a lot of article content might be the best point at which to introduce decent cash level prizes i.e. in lines of the links mentioned by you Michael.
Perhaps a Triforce Mass Effect 3 M3 Predator Full Scale Replica?
A World of Warcraft Doomhammer?
A 300 King Leonidas Helmet?
Star Wars Tie Fighter helmet?
I like the novelty aspect but they should change around constantly -- or be a choice from a list i.e. a different novelty item list each time. You really don't want Frob taking home his 16th Star Wars Tie Fighter helmet and trying to figure out what do with this one as the last one turned into a terrarium.
Might also create a Hall of champions type page with statues representing each of the winners of the quarterly prizes which alters to reflect the champions each new quarter. The graphic of the statue (placeholder again) clicks through to the profile and the statue's handheld scroll clicks through to the article.
As to yearly prizes --- this is where I think we might almost consider seeking sponsors for these awards. Make them substantive so that we create and build a lasting legacy upon which we stand here at the start of.....well okay on the bones of the last couple of decades this site has been going...but you get the idea.