When I moved into a new house, and my network became more than an access point plugged into my computer, I had to learn how to make patch cables and connect RJ-45 sockets to the CAT-5e already in the walls. This page is dedicated to the unhelpful and not-quite-helpful pages I had to wade through (before I found the pages linked to above).
Garmin sells some horribly expensive serial cables for its eTrex GPS receivers. I decided to make my own instead, as the Pfranc people (among others) also did.
(I've made this cable. I'll post a detailed description soon.)
My UPS uses the Megatec protocol to communicate over an M2505 serial cable (which the UPS vendor didn't have(!)).
(I haven't made this cable yet. I'll post an update when I do.)
If you happen to be in Delhi when the desire for cables, connectors, and stuff strikes you, I can strongly recommend a visit to:
Shreyans Computronix
106-A Vishal Bhawan,
95 Nehru Place
New Delhi 110019
+91-11-26427883
They have an extensive inventory of high-quality components at reasonable prices, and they're always polite and helpful.
Please write to ams@oryx.com if you have any questions or suggestions.