I create a subversion repository with a build environment to create a blastwave package (check the tags directory). I actually only have a tag for rrdtool-1.2.12, but I hope I'll have more in a short time. Note you can easily use the build environment for your own packages.
| blastwave/ | Contains pkginfo, copyright, depends packages files, you must edit these files | 
|---|---|
| build.prefs | variables used by the Makefile, you must edit this file | 
| Makefile | The (GNU) makefile (use /usr/sfw/bin/gmake), you usually don't need to edit it | 
| SOURCE | The package sourcename, must match the directory create by tar xfvz | 
|---|---|
| UPSTREAM | The file to extract | 
| PATH | The PATH to use by gmake | 
| CC | The C compiler to use (cc or gcc) | 
| CONFIGURE_ARGS | Configure arguments (–prefix is set from the Makefile) | 
I wrote a zsh script to compute pkg-get's catalog and descriptions files. You can find it here