If you want to limit your download and upload speeds use one of the following tools
1) Wondershaper
2) Trickle

Light and Fast Download Accelerator for Linux: Some of you may have used a download accelerator through a browser add-on but are not contented with the download speed gain. Perhaps you should try a light and fast standalone and desktop-based download manager that could help give considerable increase in download speed.Let me introduce you to Axel.

Apt-p2p gives you the ability to download Debian packages via a peer-to-peer protocol. Apt-p2p will try to get the packages from peers before it resorts to pulling them from the repository. This saves bandwidth for the repository servers, can speed up your download speed, and ads to the sense of community which Debian is so rich with.

Muon Package Management Suite is the package management application that will replace Kubuntu’s package manager when Kubuntu 11.10 is released next month. It is designed for Debian-based systems, so it could be used on similar distributions, not just on Kubuntu. In fact, it is included in the default repository of Linux Mint 11.

This tutorial shows how you can limit the CPU usage of a process with the tool cpulimit on Debian/Ubuntu. cpulimit is a simple program that attempts to limit the CPU usage of a process (expressed in percentage, not in cpu time).

MultiGet is an easy-to-use GUI download manager for ubuntu / debian linux. It is Look and work like famous windows download manager flashget.

Apt-Fast is a script which uses Axel, a command line application which accelerates HTTP/FTP downloads by using multiple sources for one file, and one can use it instead of "apt-get" on Debian based Linux distributions to get an amazing download speed improvement.

If you are in a local area network environment with a host of running Bittorrent or Gnutella, the speed of the network is significantly reduced.

I won't discuss about some complex Internet tweaking here, not that I know any :) Just a simple way to get the fastest speed you can get to download updates for your Ubuntu. How?