Count the omer with R. Yaacov Haber’s Sefiros iPhone and/or iPad app: link
Spiritual refinement through counting the omer: A practical 49 day guide to spiritual refinement through counting the Omer and the cycle of sefiros.
This is a free version of the app. There is also a paid app.
Here is another free iPhone/iPad app for counting the omer: link
Here is a free Android app for counting the omer: link
Review of the Sefiros App by Rabbi Michael Green can be found at http://bit.ly/gX9O4n
Review of the Sefiros App by Rabbi Michael Green can be found at http://rabbimichaelgreen.com/blog/2011/04/26/new-review-sefiros-iphone-app/
This article misses out on the better mobile phone apps for Sefira that are out there. Try this one:
http://iTunes.com/apps/Sefira
And this one:
https://market.android.com/details?id=com.brochos.tizkor.sefira.full&feature=search_result
Those aren’t free
But it does have a free lite version https://market.android.com/details?id=com.brochos.tizkor.sefira.lite