To start off, I am in no way affiliated with this site. I'm just excited to see something like this finally show up as I had been looking for this for a few months now (on-and-off) and stumbled upon it today :)
codepad.org is "an online compiler/interpreter, and a simple collaboration tool," according to the website. It allows you to program in it, then hit submit and it'll compile the program and display the output. It also allows you to save them (your "pastes") if you sign up, and share them with people using the link to your code. Your code can be kept either private or public (private is only accessible when given the link, public shows up on their site as a recent paste)
The only restrictions I've found is it does have a limit on output length and compile times, and there is no way to input information. EDIT: It also only compiles one file...so no separate header and source files, for example....you could always put them all together in one code with this site and separate later into files. Otherwise, it's proven to be a pretty cool tool for me as it's a lightweight site (so you could program from a phone, or any computer with internet access).
Once again, I'm not affiliated to them in any way...I'm just excited to finally find this as I get downtime occasionally and enjoy programming at night to wind down. This allows me to write up something quick while I'm out if I'm bored and save it for later use :)
Hope this proves helpful to other programmers!