Nokia has released a first batch of command line tools optimized for maemo and requested by the community. Some of these tools were available unofficially, but now they are supported and documented:

gdb - the GNU debugger
less - the familiar text file reader
iputils - containing ping, arping and tracepath for simple network analysis
screen - screen manager that multiplexes a physical terminal between several processes
strace - system call and signal tracing tool
sysklogd - utilities for system logging and kernel message trapping
traceroute - trace the route packets take to reach a network host
valgrind - a suite of tools for debugging and profiling programs (only for x86 target)
wget - a non-interactive tool for downloading files from the Web

More tools will be provided. Have a look at the roadmap and support or request the tools you need more