This AppleScript will save selected text from the current Safari window to a text file on your desktop. It uses UI Scripting, so it will only work with "enabled" versions of Panther (see Activating UI Scripting). You can use the script repeatedly and new text will be appended to the existing file. The URL and a timestamp are included to help you keep track of where the snippets came from.
tell application "Safari"
activate
set myURL to URL of document 1
end tell
tell application "System Events"
tell process "Safari"
keystroke "c" using {command down}
delay 2
set myData to (the clipboard) as text
end tell
end tell
set myDate to current date
set fPath to path to desktop
set fName to (do shell script "date \"+%Y-%m-%d\"") & ".txt"
set myFile to open for access file ((fPath as string) & fName) ¬
with write permission
write "=== " & return & "Date: " & myDate & return & ¬
"Text from: " & myURL & return & return & myData to myFile starting at eof
close access myFile
Save it to ~/Library/Scripts/Applications/Safari/ so that you can access it easily while browsing.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20040215052120323