Some little scripts I find useful:
watermark.pl : Watermark your pictures with text (such as copyrights/dates/memos etc.
findsmb.pl : Finds a file on the local SMB network in a brute-force way. It will first find all the machines on the local network that have windows shares and then search those shares for files matching a given regular expression.
s.pl : Search and replace recursively. s.pl Makefil.* -Wall -Werror will find all files matching Makefil.* and replace all occurencs of -Wall with -Werror
f.pl : Search recursively.
cdburn.sh : Burn a CD without creating a temporary ISO image
cwd.pl : Find out which processes are using a particular directory. Useful if you can't unmount because of a process.
latex_first_emph.pl : De-emphasize all the non-first occurances of a keyword in a .tex file.
mp3tocdr by David Snyder : Burns mp3s on a CD as CD tracks
msg.pl : X-chat plugin script - beeps when you get a pvt message from someone
my.pl : X-chat plugin script - sends an sms or performs an alternative action when someone joins a particular channel (eg. Alan Cox joins #kernelnewbies).
rip.sh : rips an audio CDs into mp3 format. Useful if you have a flash based mp3 player so you can carry your music around :-)