Aside from the G3/500 L2 card, how far can you go with hard drives, ram, cache, and the PCI slots? Mostly limitations, like how some older systems can't address more than a specific amount of memory (applies to hard drives and ram). I havn't found any information along these lines. Since I don't know if it's from lack of experimentation I figured i'd ask somewhere with abundant experimentation 
Dog
I'm not dead!
Okay... here we go!
RAM: 136 is the max. Two 64 MB sticks,plus the 8 on the motherboard.
HD: The main bus is IDE. I'm not sure how big it can address, though.
SCSI (internal): Up top above the CD drive is a bay cabled with SCSI. Apple made a Zip faceplate, so if you can locate that and an internal SCSI Zip 100, put that in.
OTHER:
Get the Video System card. It provides RCA and S-Video inputs. Doesn't take up a PCI slot. You should also get the Cable TV tuner card. Fits in another slot.
For Ethernet, find a CommSlot 2 ethernet card and use that, or buy a 10/100 PCI card and use it.
Add USB and Firewire on one combo card for pretty cheap. That'll use one of the two PCI slots.
Get some other speakers and plug those in, because then the internal speaker becomes a subwoofer. Perhaps use an old Multiple Scan 15" display? Those are what came with the machines, and have speakers in the sides that work nicely with the internal sub.
Good luck. This is all that I can think of right now, but I'll get back once my head is more clear and in order.
but is that all it's going to recognize? I know they use 5v EDO DIMM's and i've seen 128mb chips that fit specification so why wouldn't they work?
The memory controller in the 6500 only recognizes "banks" up to a certain size, and only accepts DIMMs with certain banking arrangements.
There's a highly technical explaination of the problem buried somewhere here:
http://www.zone6400.com
What it essentially boils down to is that putting more then 128MB of expansion RAM in a 6500 would require DIMMs composed of memory chips nobody ever manufactured.
So, yes, 128MB is the expansion RAM ceiling for those machines.
--Peace
I recently replaced the apple hd of my 6500 with a 40gb maxtor ide drive w. 5400rpm and it works fine. Ok the internal ide probably can't use the ata100 speed of the drive but anyway. I also found a internal zip and cover at ebay a few weeks ago and installed everything but i needed a extra scsi-cable adapter 'cause the internal cable was a little too short... Maybe you'll look for that first before installing a zip on the upper slot.
Nifty, cause I might be putting my 150gb into my case leaving a 20gb free for the mac. I also recently snagged a NewerTech G3/300 and 128mb with a 6400. Did some searching and it looks like putting it in a 6500 doesn't change the g3 speed, but i'm curious if the system would perform better overall in a 6500 since it has a 50mhz bus (and 275mhz cpu vs the 6400's 40/180). Eventual goal of this machine (with the TV/FM Tuner ;D) is for playing DVD's, VCD, DIVX, TV, and backup workstation (internet, word processing) when my workstation is down for experiments, upgrades, cleaning, whatever.
Dog
Not for hacking, well maybe a paintjob
Can those actually handle DVDs? Wouldn't you need a new graphics card?
I seriously doubt any upgrade to a 6x00 series machine would make it handle DVDs. (It *might* be possible with a hardware decoder board.) Even with a G3 upgrade there's no way it'll play them in software.
And of course DIVX is much worse, CPU-usage-wise, then DVD decoding is...
--Peace
happened upon this on ebay, couldn't resist.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=4607&item=4124505154
...THAT...was funny! "The blazing speed of the PowerPC 603ev processor"
The gang in the CC forum on AF 1.5 have reported using a decoder card that works fine with the 6500 MLB in PowerCCs, eudi!
jt