Q: Is there an app to close apps?

They automatically close; starting with iOS 4, apps are suspended and do NOT run in the background (unless something like a Location Service is enabled). You can double-tap your home button, and press on an app for 1-2 seconds to "kill" the applications. The means they can be deleted from your taskbar.

Simply being present on the task bar does NOT mean those apps are actually running, see

http://support.apple.com/kb/HT4211

With very few exceptions, no app can actually run in the background.  But, keeping them in the task bar means they will load faster when next used, and will return to the state they were left at when you stopped using them.

timed out - couldn\'t think of a name, mine was already taken! wrote:

 

...which I have been told can run the battery down quicker.

Who told you that?

timed out - couldn\'t think of a name, mine was already taken! wrote:

 

I have got a new one, so even though the light is on under the apps they aren't using any extra power?

Not enough to make any difference in battery performance.

timed out - couldn\'t think of a name, mine was already taken! wrote:

 

Some one at work mentioned it ages ago.

Urban legend!

Read through these to understand multi-tasking...

• http://speirs.org/blog/2012/1/2/misconceptions-about-ios-multitasking.html

• http://www.macworld.com/article/1164616/how_ios_multitasking_really_works.html

• http://whenwillapple.com/blog/2010/04/19/iphone-os-4-multitasking-explained-agai n/

• http://support.apple.com/kb/ht4211

Answering to you question, I've found this http://www.labnol.org/software/close-background-apps/20668/

Check the video, the app is called Kill, I think.

Update: Oops! It seems is no longer on the App Store.