If you're a regular user of super glue or other kinds of epoxies, you can keep the tips from drying out by storing the tubes in a jar of rice. It sounds a little backwards, but super glue actually needs water in order for it to harden and dry out.
Unfortunately, that also means that the moisture in the air can cause the tips of super glue tubes to dry out and practically ruin the whole tube. Instructables user Engineer of None has a simple fix. Just toss your super glues and epoxies in a jar filled with a tiny bit of rice and the rice will absorb a lot of the excess moisture in the air. You can also use silica kitty litter if you have some of that around.
How to Prevent Super Glue from Drying [Instructables]