I need to point out that male masturbators aren't designed to be used on women. If you are looking for something that you can use together, then a sleeve is only used on his penis and you controlling it (if you want to).
Here are some options for couple friendly toys that you can both use together.
Massager vibrators are designed to be couple friendly. You can try using a vibrator over his penis and balls. Some men love it, some hate it. But if it isn't for him, you can use it over his back and shoulders for an intimate massage or let him use it for a very intimate massage on you. The Tracey Cox massager is pretty good. Has a nice shape that would be good for mens genitals and for using over shoulders etc. It also has very deep rumbly vibrations which, personally, I love!
http://www.lovehoney.co.uk/product.cfm?p=14044
There is also this vibrator that I think is so funny and cute! Your partner surely can't say no to this! I know mine probably wouldn't!
http://www.lovehoney.co.uk/product.cfm?p=21668
Cock rings can be found with added bullets in them to stimulate your pleasure zones now. So while you have intercourse, not only will his erection be stronger and last a bit longer, but you can also have the added bonus of having vibrations against your clitoris too!
http://www.lovehoney.co.uk/product.cfm?p=14882
There is also the worlds first genuine couple use vibrator, the We-Vibe. This little vibrator is more costly, but the idea is genius. One end of the vibe goes in you, while the other end snuggles up against your clitoris, designed to add much more pleasure for you and your partner. Though it can be a hit and miss item, the people who like it, love it! Like marmite, really.
http://www.lovehoney.co.uk/product.cfm?p=14504
Love eggs are also popular. A wireless one like this can be great fun when you give your partner the controls. Not only will you get a thrill, your partner will also get a thrill knowing that he is in control of your pleasure!
http://www.lovehoney.co.uk/product.cfm?p=15667
Last but certainly not least, the power of lubricant! Unbelievably under rated, but a good lubricant can make such a difference to sex life it should be the first thing taught in sex ed classes at school!
Lube used to only be a big tub of K-Y Jelly that was only used by older couples who had lost their natural slippage! A grossed out feeling when sitting on the toilet in a friends grannys bathroom and seeing the cursed tub sitting on their shelf!
The truth is that everyone should use lube, regardless of having a bit of trouble with dryness or not! And a good quality lubricant can make such a difference and feel really good whether you are having intercourse, giving your partner a hand job or having a sensual massage or oral!
It can take some time to find the right lubricants for you, but Sliquid is a well known, high quality brand of lubricant that a lot of people like. You can also get warming lubes, cooling lubes, flavours of all sorts, thick lubes, thin lubes, lubes that heighten sensation for both partners, the list goes on.
I think it's fab how something so simple can make such a big difference!
http://www.lovehoney.co.uk/sex/lubricants/