CADDManager LISP Routines
DDSL – Download  – Dialog Display Set Layer – Type in DDSL and a list of the available layers is displayed. Double click on a layer to make it active.
DDON – Download  – Dialog Display On – Type DDON and a list of layers that are turned off are displayed. Double click on a layer to turn it on.
LLL – Download 
How to load LISP files automatically into AutoCAD session?
If you want to load your .LSP applications into every AutoCAD session, add them (either by copy/paste or by invoking (load “myApp.lsp”)) to your ACAD.LSP (or ACADDOC.LSP) file (use a text editor). Or use the StartUp Suite in the APPLOAD dialog. You can even just drag your LSP file from Windows Explorer to the Briefcase icon in the APPLOAD dialog.
Check out our LISP routine LLL to help with Lisp Loading
Jeff Sanders – http://www.jefferypsanders.com/autolisp.html 
Better than nothing – http://home.pacifier.com/~nemi/ 
XRP – generate relative paths for XREFs – Xrp2004.lsp  – created by Mark McDonough
From the author – “I wrote this for AutoCAD R14 (7 years ago) and I keep waiting for AutoCAD to fully embrace “Xref Relative Pathing”. But even with AutoCAD R2007, one still needs a utility to convert full XREF paths into relative paths. AutoCAD 2004 was the first release that allowed specifying a relative path when first attaching an XREF, it still does not allow automatic conversion of existing full XREF paths into relative paths. Nor is there any support for relative pathing for IMAGES. XRP makes the conversion of full XREF & IMAGE paths into relative paths easy. For AutoCAD R14 – R2006 (not yet tested in R2007, but feel free to give it a try). After loading the lisp file, the command name is XRP.”