I hate weaving ends in. Hate it. Hate it. Hate it. It's especially frustrating when making something large out of 50g balls. So how much do I wish someone had taught me this little trick years and years ago? You can use this to change colours (for large blocks of work) or just to join up skeins of the same colour.
This site's got the best illustrations for the join. It does take practice too.
This site was helpful with the "spit splice" hint for wool yarns. Yummy.
This one's got videos! Oooh, videos...