If you do, what specific uses do you have for it?

I use sed any time I need to do pattern substitution (including deletions by substituting something with nothing). It is great at that.

I use it pretty often, most of the time its for pattern substitution. Sometimes i use it to delete lines that are either blank or only contain spaces.

every day and in almost all my scripts. I'd be totaly lost without it.

I don't do much fancy with it, but I do do substitutions regularly. Nameservers changed? Just: Just simple stuff like that.

What kind of files are you working with?

It works on any text (ie non-binary) format file.
Personally, as per Matir I only use it for quick/simple stuff. Anything fiddly & I jump into Perl. Its my main lang these days anyway...

I installed Cygwin/X at work so I can take a directory listing of a DVD backup (of mpeg commercials) and use sed to extract just the dates & filenames, creating a .csv file. Then I'll use merge the files, sort them and use enscript to produce a postscript catalog of all of the backups. The ps2pdf program converts the postscript file to a pdf file that I save on the server. Then if someone needs a spot retrieved from backup, they just need to use "find" in acroread to find out when it was created, and on which DVD it is backed up to.

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Using comm or "grep -f" and then sed I'll create a script to delete certain files in devices, we use. To do it graphically would take days instead of minutes.

Thanks everyone