Every gym that I have trained at does it. Sometimes I do the grab the first instead of bump.
I know a purple belt that playfully was fucking with a blue belt who after they slapt hands instead of fist pumping he slapt him softly across the face with his other hand. Needless to say chaos followed. 
Slap, bump, daps, poke, tickle, wink, roll
I havnt been to my gym in a minute, but there is always alot of traffic coming through the mats and being new to BJJ i have ran the gauntlet in akward handshakes, bumps and what have yous. On a almost unrelated note, i am now experianced to expect bullrushes immediatly after the slap/bump from other white belts.
Some do slap and bump 
We do it. Some times I mix it up with the slap slap to his bump.
We used to shake hands like proper men.
Depending on who it is I do the opposite by slapping the fist and bumping the open hand. It's pretty hilarious as long as you are with a friend.
Kiss on each cheek French style followed by a pat on the butt.
Seriously never saw this until recently in Hawaii and brazillians been here for awhile.
I double slap.
Not sure why.
Yup out of hespect
We do jazz hands
been training for 11 years and don't ever remember it. I took off for a year to finish school, and when I came back everyone was adding the bump. It has been like 2 years since then and it is natural now.