During the months of January, May & September I challenge myself and any interested writers to submit at least 1 story every day to a paying market for a month. The markets are selected and checked by me (to be both open AND PAYING), the event does include Pro Paying markets.
I put up the market list on my blog normally about a month before the event to give people time to read market guidelines, select stories for them and get those ready for submission.
The rules are fairly simple. The only person who has to sub every day is me. Anyone else who wants to try is more than welcome. The markets cover SF/Fantasy/Horror/LitFic and some non-fic also. I tell people this, if you only sub once, at least it was one more than you otherwise might have. There are no guarentees of sales, but to date, everyone who has taken part has made at least once sale.
I can personally say I've made a pro sale thanks to the challenge.
The object of the challenge is to get you used to the submission process, be able to react quickly in the event a market isn't open and to deal with on-going rejections.