I couldn't recommend any mIRC bots myself, I don't use them and the only ones I ever see the point in having are eggdrop bots hosted 24/7. However, you might find luck at sites such as www.mirc.net
- they specialise in scripts mainly and so you might not find many.
There is a bots section at www.mircx.com
but they are well known for having quite a few infected scripts - I strongly recommend you run virus/trojan scans on anything you download, from that site or not. Also remember that virus scans may not pick up malicious mIRC script code - you run scripts at your own risk.
If you are interested in 'shelling out' for a shell account (sorry) then you can get info and download eggdrops from egghelp.org