Lion: Map Option + arrow to home/end
To remap home and end in Terminal, run f=~/Library/Preferences/com.apple.terminal.plist; plutil -convert xml1 $f; open $f -e, and change this:

&lt;key&gt;F729&lt;/key&gt;
&lt;string&gt;scrollToBeginningOfDocument:&lt;/string&gt;
&lt;key&gt;F72B&lt;/key&gt;
&lt;string&gt;scrollToEndOfDocument:&lt;/string&gt;


To this:

&lt;key&gt;F729&lt;/key&gt;
&lt;string&gt;&amp;#x1b;OH&lt;/string&gt;
&lt;key&gt;F72B&lt;/key&gt;
&lt;string&gt;&amp;#x1b;OF&lt;/string&gt;


To change them in normal text views, create ~/Library/KeyBindings/ and save a property list like this as DefaultKeyBinding.dict:

{
    "\UF729" = moveToBeginningOfParagraph:;
    "\UF72B" = moveToEndOfParagraph:;
    "$\UF729" = moveToBeginningOfParagraphAndModifySelection:;
    "$\UF72B" = moveToEndOfParagraphAndModifySelection:;
}


Another option would be to use KeyRemap4MacBook. See the "Use PC Style Home/End (except in Virtual Machine,RDC)" setting in https://raw.github.com/tekezo/KeyRemap4MacBook/master/Tests/lib/string/data/checkbox.xml.