Back in 2011, I wrote my first Sublime Text plugin, InsertNums. Today I'm finally releasing a new version. It's somewhat a mash up between the original InsertNums and IncrementSelection, as now you can increment through letters as well as numbers.
Ctrl+Alt+N will bring up the input panel, then just use
1 1 0
for numbers (where the first 1 is your starting number) or
a 1 0
where a is your starting letter.
One of the great side effects of introducing alpha sequences is that you can generate seemingly (but definitely not) random sequences. For instance, using
a 12345 0
will generate the following across three selections:
All that's happening there is that the next letter in the sequence is shunted across by the step amount.
Anyway, you can find InsertNums on GitHub.