Found this on the web, may come handy:

Here are some hints to help you more efficently use rapidshare. Skipping waiting time and bypassing download limits are rapidshare hacks that everybody should know.
Rapidshare has been an excellent tool for sharing large files. Recently users have discovered ways of bypassing the download limits and skipping the waiting time. Here are a description of these methods.

Update: Two new methods of bypassing download limits have been posted. These are more advanced and may require additional software or hardware, but you should check them out when you are done with these easier methods:

RapidShare: NIC tricks and MAC cloning to bypass download limit

Rapidshare traces the users IP address to limit each user to a certain amount of downloading per day. To get around this, you need to show the rapidshare server a different IP address.

Here are some methods for doing this:

1. Short-Out the javascript:

1. Goto the page you want to download
2. Select FREE button
3. In the address bar put the following: javascript:alert(c=0)
4. Click OK
5. Click OK to the pop-up box
6. Enter the captcha
7. Download Your File

2. Request a new IP address from your ISP server.

Here's how to do it in windows:
1. Click Start
2. Click run
3. In the run box type cmd.exe and click OK
4. When the command prompt opens type the following. ENTER after each new line.
ipconfig /flushdns
ipconfig /release
ipconfig /renew
exit

5. Erase your cookies in whatever browser you are using.
6. Try the rapidshare download again.

Frequently you will be assigned a new IP address when this happens. Sometime you will, sometimes you will not. If you are on a fixed IP address, this method will not work. To be honest, I do not know how to do this in linux/unix/etc. If this works for you, you may want to save the above commands into a batch file, and just run it when you need it.

3. Use a proxy with SwitchProxy and Firefox:

1. Download and install Firefox if you have not already
2. Download and install SwitchProxy
3. Google for free proxies
4. When you hit your download limit, clean your cookies and change your proxy

4. Use an anonymous service:

Running your system through the tor network should in theory work; however, it is difficult to use and setup. Plus, you allow others to run their evil deeds through your system as well by using this system. Anonymizer 2005 is inexpensive, easy to use, but not free. Other pay services would likely work as well.

5. You can use a bookmarklet to stop your wait times:

1. Open IE
2. Right Click On This Link
3. Select Add to Favorites
4. Select Yes to the warning that the bookmark may be unsafe.
5. Name it "RapidShare No Wait"
6. Click on the Links folder (if you want to display it in your IE toolbar)
7. Click OK
8. You may need to close and reopen IE to see it
9. Goto rapidshare and click the bookmarklet when you are forced to wait