Just out of curiosity, how many do you have installed on your main PC? And how many do you actually use?

I only have one right now (Ubuntu 6.06.1 LTS) but when I get my new rig set up, I'm planning to go install as many distros as I can, and maybe FreeBSD and ReactOS.

And it's possible to share /home partitions, right? But how do I do that?

Just two,

****XP32 -> Gaming
****FC64 -> Everything else

Slack 11, Ubuntu 7.04, FC6.

I mainly use Slack but tinker around with the others as well as having a spare partition for playing with various others.

See my sig.

I currently have:
-Slackware 11 (which I mainly use)
-Suse 10.0 ( an almost 3 year old install, which started running a bit slow, I rarely use it, I plan on formatting it and getting something else on...)
-Windows XP (for Skype and AutoCAD)
-a virtual XP in Virtual Box(trying to get rid of it on my main hard drive, but I can't seem to get the webcam working in the virtual one).

When I manage to make some space on my hard drive, or get a new computer, I plan on installing:
- Slackware
- Gentoo
- something Debian-based. I haven't decided yet.
- FreeBSD
- Solaris
- Numerous others ran in a virtual machine, for testing purposes.

I want Slackware because I like it and I'm used to it, and I want to get to know the others better as well.

One.

I don't have a need for more.

To answer your question, one at a time.

LMAO that's pretty close to what my original answer was going to be.

3, Slackware 11, FreeBSD 6.2 and Win XP.

/*
EDIT: Nope, Win 2000 Professional has replaced XP now after the very confused and computer-illiterate individual I have over this week somehow managed to get 3 viruses, 4 trojans and a couple of rootkits on it.

>.< >.< >.< >.< >.< >.< >.< dammit...
*/

Got two on my laptop, Ubuntu and Vista (haven't got the heart to delete it, it's just sitting there and I boot it up once in a while for people who've never used vista or to run windows update).

On my desktop I just run Debian.

i run one OS Ubuntu 7.04 with virtual box and vmware installed. and i run my windows xp virtual machine and another CentOS 4.4 installation for software testing. i think visualization is the way to go when it comes to running more than one OS on the same box. just buy you a aditional chip of memory. i don't like multiboot.

3: Suse and Win XP (ouch!) on one laptop. Just installed Debian Etch on the other home laptop (bye bye Slackware...). Actually, I can still boot into Slack, so that makes it 4.

if i install GRUBor LILO in the same partition (not MBR) then how can i boot from that partition??

Depends on what you mean by the phrase 'installed'. Currently I have five Operating Systems installed. Most of the time I only use one, sometimes I have as many as four 'booted and running', virtual workstations sure are nice!!!

The easiest solution is to use a single bootloader installed to the MBR and set it up to boot all of the operating systems you have installed.