Participation info including its advantages:
I am retired and do this as volunteer work basically. My benefit is loving to practice, jam jazz, meet like minded people and socialize. I spend about 3 days work to put on a jam, mix down the recordings and distribute them. You get the same benefits I get but with zero work except your practice, showing up and playing. I do all the work you do as well but at 8 hours a day practice I probably practice more than most who show up.
Jams are not advertised. You get a bit of low pressure performing experience.
If you are visiting from outside Toronto you can also become a member and be scheduled to jam. Kay is a member from Melbourne Australia who jammed once.
Since our jams are at a struggling restaurant the jam space is almost free because you get something in return for your money (great food and beverages which you can take home after the jam if you wish). We take up a fair bit of space for a really long time and we don't draw a large crowd so members buy stuff hoping the restaurant won't kick us out.
No need to bring an amp. You plug directly into the mixer. Standard effects are available. You can even plug in a special effect box. Members who want to hear their amp can sit with their amp on a chair pointing directly at them. Having jam sharing helps since members out front can help us set the mix.  I have a special procedure to try and get a good PA system to drums mix as well.
I record all jams directly to a disk drive which is attached to the mixing board so the recordings are high quality. Members get to hear the recordings on sound cloud. Jam participants can download an mp3 copy of each song from the web if they wish. Some members like this since they like to critique their playing. I suspect these will bring back some fond memories in the future for many members.
Supreme Restaurant And Bar is a small location so drummers need a 3x3 drum kit. When attendance gets high enough I hope to get a location with a bigger stage. Drums are miked for the recording but not amplified out the P.A.
I use filler music while I set up for the next song so the audience does not complain about silence. The filler music consists of our better jam recordings. I pick songs so you can hear your playing at prior jams. This helps make the 3 to 4 minute wait between songs easy to take for both the players and audience. This is so much more fun than searching fake books for new songs during prime jam time. It's a conversation starter to.
Your privacy is respected. The only thing that appears on the website is your first name, your initials and your instrument(s). I have your email address so you can get the various jam notification emails. I take pictures of the jams for Facebook so potential new members know the jams are fairly popular. I have no idea where anyone lives nor can I phone them.
I use Band In A Box to fill in for missing players at times. It might be useful to know BIAB can be made to do a lot of things a band can do (change speed mid song, change style mid song, special endings, endings that allow musicians to do their thing at the end, full chorus loops of your actual playing, etc). You can always make up a BIAB file like this and send it to me to be used at the jam. I would name it such that I know it is your BIAB file and if appropriate reuse it each time you request that song.
I put a lot of emphasis on the jam being fair for all (allowing members equal chance to select songs to build the jam schedule, restricting members to 1 solo each unless the song is short then 2 or 3 solos each, distributing extra song requests equally). As a result the only people who joing are people who think being fair is good. As a result you will find that the people who come out are nice easy going kind people. This makes for a more enjoyable jam.
The people at Supreme Restaurant & Bar kick out annoying customers that could make a jam unpleasant. I have seen this with my own eyes. They do it in a respectful manor so as not to create enemies. I feel very comfortable at that location.