I have been waiting for them to update me with advertisers for my 3 different domains and nothing. They haven't even replied to my email.
im with matched... infact i got 28 people to join last month only 4 of them have got advertisers so far. I know this but the £20 in my account £5 for each refferal thats matched with an advertiser. So 3 weeks is nothing, think about ti once you get an advertiser your getting £3? if i remember right a month for showing thier banenr thats basicly your hosting each month just for one site url getting an advertiser, its worth the wait in the end.
I've found that the best way to get some ads quickly and to start earning $$$ is to submit sites that have something to do with finance, insurance or health!
I'm waiting for more than 3 months for one of my webmaster site.. Their ads are for SEO purposes... There are some other networks similar to matched.co.uk.. One such similar site worked well for me.. Here I explained it... http://forums.digitalpoint.com/showthread.php?t=1017150
Just patient, they still crawling your pages and then find the suitable advertisers for your pages. Such as Jake_J said, just submit pages related to finance and insurance, or something like them. you may also submit pages related to health and travel. Good luck!