I have a set, more from curiosity than anything else. Not really worth the disappointment if you enlarge much. Some do seem to be better than others.
Now, if you really want some odd effects, look for front element wide/tele optics made for video cameras. I have a reversible one with a 46mm thread that mounts onto a bay 1 to 46mm filter thread adapter. The wide direction has edge curvature like a fish-eye. Resolution and aberration correction is not worth much, though, as they were designed with a video camera optical setup in mind, not 6x6.
On the close-up lenses - you should be able to find Bay 1 sets of +1, +2, and +3 (focus distances of 1 metre, 50 cm, and 33cm.). They come as pair - a simple meniscus lens for the taking lens, and a meniscus plus prism unit for the viewing lens. You do get a little parallax as the YashicaMat lenses are 45mm apart and the viewing lens is looking down a bit due to the prism, which is why there is an index mark to get it the right way up!
I keep a set in a little leather case on the strap of my YashicaMat for those times I need to get closer than the 3.5 feet minimum focus. I think the +2 set gets the most use for me. Once you get to +3 parallax can be a real problem. My Mamiya C Paramender has a 45mm mark added to the column for use with the Rollei/Yashica design TLRs. It's how I got it.