During the Swords & Wizardry/Majestic Wilderlands campaign I ran for the past several years, my players (Dwayne, Tim, Rusty Battle Axe) and I decided that we didn't like the weird bumps that are in the regular XP charts. In addition I wanted to some up with a consistent set of charts that I could use in future books for new classes.
You can download the result of what we created together
Standard XP Charts
To use them with existing classes note the XP required to reach second level and that the chart to use. There are charts for 2nd level at 1,500 xp, 1,750 xp, 2,000 xp, 2,250 xp, 2,500xp, 2,750 xp, and 3,000 xp. The charts also displays the total xp required to go from one level to the next. This also show the method to our madness in creating these.
Hope you find some use for them.