If you fear you might forget to count the Omer, you can subscribe to the OU Sefirah Reminder Daily email. They will send you an email every day to remind you which day to count that evening. They also provide explanations and the basic laws of Sefirat HaOmer.
This is the second time I’ve used it and I find it quite useful, especially after a few weeks have passed and you have lost count.
Hannah's Nook 
i actually got my dad to write an omer counter in javascript for my blog. it was actually kinda hard, he said, but a fun challenge. it’s not perfect, though, because it can’t change at sundown, it changes at midnight…but that’s okay, i know what it means.
I will try not to forget with this tool.
I need to get a physical omer-counting calendar, I know a friend has one. I signed up for the Chabad reminder, but yikes. I’ve faltered! Thanks for the tip 🙂