Because of walls and such I cannot use my wireless network throughout the house. I even have purchased a repeater. Are there any tricks (maybe connecting a special antenna to the repeater) that would increase my range?
Wifi is a lot wimpier than many people realize, especially if to has to punch through walls. If the repeater doesn’t help, you might want to try a directional “Pringles can” style antenna.
Are you aiming for increased performance in just one direction? If this is the case, check out the links below.
I haven’t had the need to make any of these myself, but if I do, I’m trying them first.
The simple version needs tinfoil, and two sheets of stiff paper.
The slightly more complicated version needs some wood or something. I like their gallery. 
If you have something popular like the Linksys WRT54G, third-party firmware is available, that will let you kick up the transmit power.
How much space are you looking to cover that a repeater was ineffective?
It’s only about 100 feet, but includes several walls. With a laptop I get weak and dropped signals there so I though I repeater should do the trick. I have a dlink 624.
Tell me more!
These guys are supposed to sell some pretty intense gear. You can pretty much punch a signal through any wall for miles around with the stuff they sell, at least according to what Make Daisey said on The Screensavers a couple of months back. (Hint: Be sure to check the “Yes I am in the military” box on the order form.)
Well, I just finished a project setting up an old building with Wireless Access Points (WAPs) the place was pretty broke, so I set them up with Belkin 802.11G wireless access points - browse em here.
Worked pretty good, even through heavy walls - I won’t go into the gorey details, but you could put one WAP in the middle of your house - the bottleneck even with 802.11b is going to be the internet, not the wireless network, so you should be fine. Unless you have a server or have a peer-to-peer network, it should be more than enough. Just make sure you have the latest firmware for everything, are on teh right channel, etc.
For the WRT54G and GS: http://www.hyperdrive.be/hyperwrt/