diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..eccaa1f
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+graphpkg
diff --git a/README.md b/README.md
index 36e97ca..758544c 100644
--- a/README.md
+++ b/README.md
@@ -1,15 +1,53 @@
 # Installation
 
-	go get github.com/davecheney/graphpkg
+```sh
+# davecheney's original
+go get github.com/davecheney/graphpkg
+
+# or jbenet's fork
+go get github.com/davecheney/graphpkg
+```
 
 # Usage
 
 To graph the dependencies of the net package:
 
-	x-www-browser $(graphpkg net)
+```
+x-www-browser $(graphpkg net)
+```
+
+
+```
+> graphpkg
+usage: graphpkg [flags] <package name>
+
+  -browser=false: open a browser with the output
+  -format="dot-svg": format: {dot, dot-*, d3json}
+  -match=".*": filter packages
+```
 
 # Filtering
 
 graphpkg can also filter out packages that do not match the supplied regex, this may improve the readability of some graphs by excluding the std library:
 
-	x-www-browser $(graphpkg -match 'launchpad.net' launchpad.net/goamz/s3)
+	graphpkg -match 'launchpad.net' launchpad.net/goamz/s3
+
+
+# Examples
+
+```
+> graphpkg -format=dot-svg -browset
+opening in your browser...
+
+> graphpkg -format=dot runtime
+digraph {
+  N0 [label="unsafe",shape=box];
+  N1 [label="runtime",shape=box];
+  N1 -> N0 [weight=1];
+}
+
+> graphpkg -format=d3json runtime
+[{"name":"runtime","size":1000,"imports":["unsafe"]}
+,{"name":"unsafe","size":1000}
+]
+```
diff --git a/encoding.go b/encoding.go
new file mode 100644
index 0000000..7996702
--- /dev/null
+++ b/encoding.go
@@ -0,0 +1,111 @@
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"os"
+	"os/exec"
+)
+
+func allKeys(pkgs *map[string][]string) []string {
+	keys := make(map[string]bool)
+	for k, v := range *pkgs {
+		keys[k] = true
+		for _, v := range v {
+			keys[v] = true
+		}
+	}
+	v := make([]string, 0, len(keys))
+	for k, _ := range keys {
+		v = append(v, k)
+	}
+	return v
+}
+
+func keys(pkgs *map[string][]string) map[string]int {
+	m := make(map[string]int)
+	for i, k := range allKeys(pkgs) {
+		m[k] = i
+	}
+	return m
+}
+
+// writeDotRaw outputs the import graph as dot
+func writeDotRaw(w io.Writer, pkgs *map[string][]string) error {
+	fmt.Fprint(w, "digraph {\n")
+	keys := keys(pkgs)
+	for p, i := range keys {
+		fmt.Fprintf(w, "\tN%d [label=%q,shape=box];\n", i, p)
+	}
+	for k, v := range *pkgs {
+		for _, p := range v {
+			fmt.Fprintf(w, "\tN%d -> N%d [weight=1];\n", keys[k], keys[p])
+		}
+	}
+	fmt.Fprintf(w, "}\n")
+	return nil
+}
+
+// writeDotOutput uses graphviz's dot util to convert dot fmt into something else
+func writeDotOutput(out io.Writer, fmt string, pkgs *map[string][]string) error {
+	cmd := exec.Command("dot", "-T"+fmt)
+	cmd.Stdout = out // write dot's output straight to ours.
+	cmd.Stderr = os.Stderr
+
+	in, err := cmd.StdinPipe()
+	if err != nil {
+		return err
+	}
+
+	if err := cmd.Start(); err != nil {
+		return err
+	}
+
+	// write dot fmt into dot's input
+	if err := writeDotRaw(in, pkgs); err != nil {
+		return err
+	}
+	in.Close()
+	return cmd.Wait()
+}
+
+type d3pkg struct {
+	Name    string   `json:"name,omitempty"`
+	Size    int      `json:"size,omitempty"`
+	Imports []string `json:"imports,omitempty"`
+}
+
+// writeD3JSON outputs the import graph as mbostock's json imports thing
+func writeD3JSON(w io.Writer, pkgs *map[string][]string) error {
+	d3pkgs := pkgsToD3Pkgs(pkgs)
+	enc := json.NewEncoder(w)
+
+	w.Write([]byte("["))
+	first := true
+	for _, p := range *d3pkgs {
+		if first {
+			first = false
+		} else {
+			w.Write([]byte(","))
+		}
+
+		if err := enc.Encode(p); err != nil {
+			return err
+		}
+	}
+	w.Write([]byte("]"))
+	return nil
+}
+
+func pkgsToD3Pkgs(pkgs *map[string][]string) *map[string]d3pkg {
+	d3pkgs := make(map[string]d3pkg)
+	for p, imports := range *pkgs {
+		d3pkgs[p] = d3pkg{
+			Name:    p,
+			Size:    1000, // change this once we know wtf it is.
+			Imports: imports,
+		}
+	}
+	return &d3pkgs
+}
diff --git a/main.go b/main.go
index 7c2aa48..e719536 100644
--- a/main.go
+++ b/main.go
@@ -1,5 +1,5 @@
 // Graphpkg produces an svg graph of the dependency tree of a package
-// 
+//
 // Requires
 // - dot (graphviz)
 //
@@ -12,18 +12,21 @@ import (
 	"flag"
 	"fmt"
 	"go/build"
+	"io"
 	"log"
 	"os"
-	"os/exec"
 	"regexp"
+	"strings"
 
 	"github.com/pkg/browser"
 )
 
 var (
-	pkgs     = make(map[string][]string)
-	matchvar = flag.String("match", ".*", "filter packages")
-	pkgmatch *regexp.Regexp
+	pkgs       = make(map[string][]string)
+	matchvar   = flag.String("match", ".*", "filter packages")
+	browservar = flag.Bool("browser", false, "open a browser with the output")
+	formatvar  = flag.String("format", "dot-svg", "format: {dot, dot-*, d3json}")
+	pkgmatch   *regexp.Regexp
 )
 
 func findImport(p string) {
@@ -59,30 +62,11 @@ func filter(s []string) []string {
 	return r
 }
 
-func allKeys() []string {
-	keys := make(map[string]bool)
-	for k, v := range pkgs {
-		keys[k] = true
-		for _, v := range v {
-			keys[v] = true
-		}
-	}
-	v := make([]string, 0, len(keys))
-	for k, _ := range keys {
-		v = append(v, k)
-	}
-	return v
-}
-
-func keys() map[string]int {
-	m := make(map[string]int)
-	for i, k := range allKeys() {
-		m[k] = i
-	}
-	return m
-}
-
 func init() {
+	flag.Usage = func() {
+		fmt.Fprintf(os.Stderr, "usage: %s [flags] <package name>\n\n", os.Args[0])
+		flag.PrintDefaults()
+	}
 	flag.Parse()
 	pkgmatch = regexp.MustCompile(*matchvar)
 }
@@ -94,30 +78,49 @@ func check(err error) {
 }
 
 func main() {
-	for _, pkg := range flag.Args() {
+	args := flag.Args()
+	if len(args) == 0 {
+		flag.Usage()
+		os.Exit(1)
+	}
+
+	for _, pkg := range args {
 		findImport(pkg)
 	}
-	cmd := exec.Command("dot", "-Tsvg")
-	in, err := cmd.StdinPipe()
+
+	r, w, err := os.Pipe()
 	check(err)
-	out, err := cmd.StdoutPipe()
-	cmd.Stderr = os.Stderr
-	check(cmd.Start())
 
-	fmt.Fprintf(in, "digraph {\n")
-	keys := keys()
-	for p, i := range keys {
-		fmt.Fprintf(in, "\tN%d [label=%q,shape=box];\n", i, p)
-	}
-	for k, v := range pkgs {
-		for _, p := range v {
-			fmt.Fprintf(in, "\tN%d -> N%d [weight=1];\n", keys[k], keys[p])
-		}
-	}
-	fmt.Fprintf(in, "}\n")
-	in.Close()
+	// run the transform
+	go xform(w)
+	output(r)
+}
 
-	go browser.OpenReader(out)
+func xform(w io.WriteCloser) {
+	var err error
+	switch {
+	case *formatvar == "d3json":
+		err = writeD3JSON(w, &pkgs)
+	case *formatvar == "dot":
+		err = writeDotRaw(w, &pkgs)
+	case strings.HasPrefix(*formatvar, "dot-"):
+		f := (*formatvar)[4:]
+		err = writeDotOutput(w, f, &pkgs)
+	default:
+		err = fmt.Errorf("error: unknown format %s", *formatvar)
+	}
+	w.Close()
+	check(err)
+}
 
-	check(cmd.Wait())
+func output(r io.Reader) {
+	var err error
+	switch {
+	case *browservar:
+		fmt.Println("opening in your browser...")
+		err = browser.OpenReader(r)
+	default:
+		_, err = io.Copy(os.Stdout, r)
+	}
+	check(err)
 }