So one of the issue with Prepaid is that somehow your credits will slowly stack up if your usage is lower than the amount that you reload(RM30/31 depending on the calendar month). So apart from the conventional ways like subscribing for a data plan, super long life, and credit transfer, here's some other ways to use your credit for things that you may not know of 

Disclaimer: this list is compiled from the various sources from the Internet, I've yet to try any of it(but I'll try the first one soon though  )

1. Buy Google Play Store App
Supported by: DiGi
Source: http://new.digi.com.my/ecomm_C/services/default/google-play (Read "How to Get it")

2. Mol Point
Supported by: Maxis, Celcom, DiGi
Source: http://www.mol.com/Reload/Faq/215

3. @Cash (can be used for MapleStory, Cabal, Audition)
Supported by: Hotlink
Source: http://www.playpark.com/sg/page/guide_charging_AP_maxis

4. Windows Phone Store App
Supported by: DiGi
Source: https://amanz.my/201355954/

5. Blackberry Store App
Supported by: DiGi
Source: http://new.digi.com.my/ecomm_C/services/de...Carrier_Billing

6. Garena
Supported by: DiGi, Hotlink
Source: http://pay.garena.my/

7. Celcom Air Cash (can be used for 11street payment)
Supported by: Celcom
Source: https://aircash.celcom.com.my/aircash/Main.html
Credits: FourZeroFour

So how about that? know of any other ways of burning your credits? Share it here 

Celcom has AirCash like @Cash to Hotlink. You can buy reload credit, send money to another AirCash user and purchase stuff on 11street.my

2. If you look at the link it does seem possible to buy molpoint using credit via easy2pay

I'll look up at the rest later

EDIT: It seems like you can do it vice versa(buy mol point using phone credit and buy phone credit using mol point)

3. Still available I guess, https://www.google.com/search?q=%40cash+hot...tlink&tbs=qdr:y most of the links are still from this year

Added more options which are Steam Wallet, Google Play Gift Card, iTunes Gift Card and Battle Net Gift Card provided by codashop