I found a free Minecraft server hosting tool that gives 8GB of RAM.
The first step looks a bit harder than other hosts but it sounds like it is worth it if you stick with it.
Free 8GB RAM Server Hosting Hack
GG.MINEWIND.NET New Server IPSUPERB BOOMCRAFTY MODPACK SERVER
I found a Minecraft server that is all about the Boomcrafty modpack.
The main thing here is playing modded Minecraft together and using the modpack for the full experience.
If you want more info it points to the Boomcrafty modpack page.
GG.MINEWIND.NET New Server IP