Most smart phones or portable devices have some form of accessibility option that allows for text to speech.
Where they are insufficient there are also a number of accessibility apps for e-reading, which allow blind or partially sighted readers access to the written word via text to speech.
Many of these do this by ocr scanning text, with users using their devices’ camera to read text which is then spoken. Sighted users can also find this useful as many also translate, so its a great app when travelling in countries that choose not to speak Australian.
Other apps read out downloaded files in any formats, or read webpages on demand.
These text to speech readers again are also useful for sighted users as they can be used as audio books while driving or anywhere.
A useful listing and review of literacy and accessibility apps for iphone/ipad can be found on the Spectronics website at: http://www.spectronicsinoz.com/article/apps-for-literacy-support
There are also a number of apps for Android.
I haven’t listed them or revewed them. But the apps produced by the Disability support company IDEAL Group at: https://market.android.com/developer?pub=IDEAL+Group,+Inc.+Android+Development+Team are good.
Just doing a search on Android market under ‘ocr’, or ‘accessibility’, ‘text to speech’ etc. will also find many.