One really nice feature of maven is the dependency resolution stuff that it does. The dependency plugin also has an analyse goal that can detect a number of problems with your dependencies. It can detect libraries you use but haven't declared in your POM, but work through transitive dependencies. This can cause build problems when you remove the library that was dragging in the undeclared dependency. It can also work out which dependencies you are no longer using, but have a declared dependency.

mojo-jojo david% mvn dependency:analyze
[INFO] Scanning for projects...
...
[INFO] [dependency:analyze]
[WARNING] Used undeclared dependencies found:
[WARNING]    commons-collections:commons-collections:jar:3.2:compile
[WARNING]    commons-validator:commons-validator:jar:1.3.1:compile
[WARNING]    org.apache.myfaces.core:myfaces-api:jar:1.2.6:compile
[WARNING] Unused declared dependencies found:
[WARNING]    javax.faces:jsf-api:jar:1.2_02:compile
...

How not to configure your DNS

david% dig -x 190.208.19.230

; <<>> DiG 9.4.2-P2 <<>> -x 190.208.19.230
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 35398
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;230.19.208.190.in-addr.arpa.   IN      PTR

;; ANSWER SECTION:
230.19.208.190.in-addr.arpa. 3600 IN    PTR     190.208.19.230.

;; Query time: 253 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: Fri Apr 10 10:00:21 2009
;; MSG SIZE  rcvd: 73

Whoops