I second YUMI. It simplifies the whole process of carrying a bootable OS in the flash drive by keeping all Linux files and folders nested under a single root folder.

MJ, you CAN save personal data in the free space without interfering with the Live OS on the flash drive.

thanks for mentioning this Stivinn.

i knew this , and so i had tried it twice with two of LiveUSBs i created some time back . copied some random files after creating the Live device .

and both of them did falter  .

one stopped booting , and one booted but dint work well !

and so i refrain from putting any thing else on them .

Hmm.. What distributions were you working with? And how did you make the Live environment? Did you try LiLi or YUMI?

on one pen drive it was ubuntu , created live with i think UnetBootin or Universal USB installer .

it booted fine , but after i copied some files on to the drive , it booted , but on the options screen of the start menu , after i clicked on the Start Ubuntu , it dint went forward . the screen just went blank .

and the second one was i think Puppy linux . created same way .

and once even GPart live also was done the same way .

never tried YUMI .  ....

Seems like the copying process on your drive wasn't free from errors or inadvertently, some of the root files got replaced/corrupted/deleted. I say this because I've tried Ubuntu 10.10 on my flash drive over a period of an year using UNetBootin, Yumi, and LiLi and gave 11.10 a try using Wubi without any problems with saving personal files. Also, I've been using various flavours of Puppy Linux on flash drives for a long time now. I've experimented quite a bit with various tools, and made a few of my friends very interested in Puppy. It is the best suited distro to 'get your job done' from a flash drive, it has fewest write cycles, has its own persistence file and operated totally from the RAM. Never heard from them about the problems that you mentioned. One friend of mine uses her Puppy-USB to remove viruses from her flash drive before using it in Windows.

IMHO, YUMI is the go to solution for using multiple distros on one media effortlessly. You should definitely give it a try. Also, scan your pen drive thoroughly for errors.  My external hard drive has Ubuntu, Clonezilla and Puppy all in Live mode using YUMI. At the moment though, YUMI's support is limited to a quite a small list of distros.

yup , thats right about Puppy . its a good one .

i keep a Live Puppy drive with me all the time and use it especially when i need to access the net on a computer thats not mine . i wouldnt trust any other PC except my own and that is where Puppy gets the 'Job Done' !

and other than that , there are plenty of other times  when a live linux drive comes in handy .

Ubuntu i just tried for fun purposes .

and you might be right about the root files getting corrupted on the Live drive , but i never did investigate it thoroughly .

any ways thanks for the suggestion about YUMI . 

definitely will give it a try :)